In every four-year cycle of Bitcoin—especially in the six months leading up to a halving—the debate over the sustainability of its security model resurfaces. This discussion centers on two opposing views: one argues that Bitcoin’s security model is inherently sound and sufficient for long-term stability, while the other contends that its deflationary monetary policy and reliance on rising transaction fees are unsustainable, potentially undermining network security.
While many in the Bitcoin community consider this issue resolved or negligible, the reality is far more nuanced. It involves deep technical, economic, and game-theoretical considerations. This article presents a balanced analysis of both perspectives, exploring how Bitcoin and CKB—Nervos’ foundational blockchain—approach long-term security through fundamentally different models.
Understanding Proof-of-Work (PoW)
Bitcoin operates as a public ledger maintained by a decentralized network of computers called nodes. To achieve consensus on the state of the blockchain, nodes rely on Proof-of-Work (PoW)—a consensus mechanism where specialized participants known as miners validate and record transactions.
Miners compete to solve a cryptographic puzzle based on the SHA-256 hashing function. Every ten minutes, on average, a miner discovers a valid solution—a hash output below a dynamically adjusted target—and broadcasts a new block containing recent transactions. Each block cryptographically links to the previous one, forming an immutable chain.
The integrity of the blockchain stems from this design: altering any historical block would require re-mining all subsequent blocks, an effort demanding immense computational power.
A transaction gains credibility once it’s included in a block. The more blocks built atop it (i.e., confirmations), the more irreversible it becomes. To find a valid hash, miners repeatedly adjust a random value called a nonce until the hash meets the difficulty target.
For example:
- "I Love Nervos" →
4cdf9079fe156321c82e026e263032d2e826a9abca07d0cca44f773ff0f66285 - "I Love Nervos 1" →
955146eb7dfa0d263b0fc8d943f642e26524435ae63a894a6f1879a259db0487
Even minor input changes yield vastly different outputs. Miners use specialized ASIC hardware to perform trillions of hash attempts per second. This energy-intensive process ensures that only those who invest real resources can add blocks—hence “proof of work.”
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Bitcoin’s Security Budget: Subsidy vs. Fees
Miners are rewarded for their efforts through block rewards, composed of two parts:
- Block subsidy: Newly minted BTC (currently 6.25 BTC per block).
- Transaction fees: Payments from users for including their transactions.
These rewards incentivize miners to secure the network. The cost of launching a 51% attack—gaining majority control of the network’s hash rate—rises with the total mining expenditure. Thus, miner revenue directly determines Bitcoin’s security level.
Currently, Bitcoin’s daily security budget is approximately $25.6 million, with 97% coming from block subsidies and only 3% from fees. This means that if attack costs scale with miner revenue, today’s network would require hundreds of millions of dollars in operational costs alone to compromise.
However, the block subsidy halves every 210,000 blocks (~four years), eventually reaching zero by 2140. This raises a critical question: Can transaction fees alone sustain Bitcoin’s security once subsidies disappear?
To maintain current security levels without subsidies, average fees would need to rise dramatically:
- At today’s market cap: ~$85 per transaction.
- At a $5 trillion market cap: ~$850 per transaction.
Yet historically, average fees have hovered around $2, spiking only during bull market peaks.
The Role of Transaction Fees: Optimism vs. Pessimism
The Optimistic View
Proponents believe that as Bitcoin becomes a global settlement layer, demand for its scarce block space will surge. High-value transactions—such as institutional settlements or inter-Layer 2 reconciliations—will drive fees upward naturally.
Projects like BitVM and Rollkit could expand Bitcoin’s utility beyond simple transfers, enabling complex computations and data availability services. These innovations may justify premium fees, especially if Bitcoin becomes the ultimate trust anchor for other systems.
Additionally, most small payments are expected to occur off-chain via Lightning Network, reducing congestion while preserving on-chain security for final settlement.
The Pessimistic View
Critics argue that high fees contradict Bitcoin’s purpose as a decentralized store of value. Users may hold BTC but resist paying exorbitant fees to move it. Economic principles like price elasticity of demand suggest that over time, users seek cheaper alternatives.
Moreover, fee-based income is volatile. Unlike predictable subsidies, fees fluctuate with usage patterns. This unpredictability could lead to instability:
- Low activity → low fees → reduced mining incentives → lower security.
- Lower security → reduced user confidence → fewer transactions → even lower fees.
This feedback loop creates a potential death spiral: declining security erodes trust, further reducing usage and revenue.
Measuring Security: The Importance of Security Ratio
Rather than focusing solely on absolute spending, a more meaningful metric is the security ratio—the cost of attack relative to network value.
Today, attacking Bitcoin costs about 0.22% of its market cap hourly. If market cap grows tenfold without increased attack cost, that ratio drops to 0.022%, potentially making attacks economically feasible.
Thus, long-term security depends not just on miner income but on maintaining a sufficient security ratio—something increasingly difficult without stable revenue sources.
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51% Attacks: Risks and Realities
A 51% attacker can:
- Perform double-spends.
- Censor transactions.
- Mine empty blocks.
- Mislead lightweight (SPV) clients.
The longest chain rule ensures consensus: nodes accept the chain requiring the most computational work. But with majority hash power, an attacker can outpace honest miners and rewrite history.
Some suggest users can mitigate risk by waiting for more confirmations (e.g., 60 instead of 6). However, if an attacker controls enough resources to fund the entire security budget, no number of confirmations guarantees safety. Honest miners would eventually capitulate, collapsing network security entirely.
Beyond Rational Actors: Non-Economic Threats
Many assume miners act rationally—prioritizing profit over destruction. But what if an actor seeks disruption for ideological, political, or strategic reasons?
While such scenarios are unlikely due to high economic and social costs, they highlight a key truth: security must withstand irrational threats too. The higher the security budget, the more prohibitive any attack becomes—even for well-resourced adversaries.
CKB’s Alternative: Sustainable Security Through State-Based Incentives
Nervos’ Common Knowledge Base (CKB) offers a novel approach to long-term security by aligning economic incentives with network usage.
Like Bitcoin, CKB uses PoW and has a capped supply via primary issuance, which halves periodically until fully distributed. But it introduces secondary issuance: a fixed annual emission of 13.44 billion CKB, distributed based on on-chain activity.
Crucially:
- Miners receive part of secondary issuance proportional to network usage.
- Users who lock CKB in Nervos DAO earn yield and hedge against inflation.
- The rest is burned or allocated to treasury.
This model ensures predictable miner income regardless of transaction volume.
Two Key Innovations
- Sustainable Security Funding
Instead of relying on volatile fees, CKB compensates miners through inflation tied to state usage. Those occupying chain space (e.g., storing data) effectively pay an “inflation tax,” funding ongoing security. - Solving the Tragedy of the Commons
On CKB, each CKB token represents one byte of storage capacity. Holding CKB grants the right to use state space—making it scarce and privately owned. This discourages bloat and encourages efficient resource use.
As more value is stored on CKB, demand for space increases, boosting miner rewards and attracting more hash power—a positive feedback loop between value storage and security.
Unlike Bitcoin, where security depends on transaction throughput, CKB’s security scales with stored value, making it ideal for a long-term store of value.
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Frequently Asked Questions
Q: Why is Bitcoin's reliance on transaction fees risky?
A: Transaction fees are volatile and subject to demand fluctuations. If fees drop due to low usage or competition from Layer 2 solutions, miner revenue falls—potentially weakening network security over time.
Q: How does CKB prevent state bloat?
A: CKB ties ownership of state space directly to token holdings—one CKB equals one byte of storage. This creates economic disincentives for hoarding unnecessary data and promotes efficient use of blockchain resources.
Q: Can Bitcoin survive without block subsidies?
A: It’s uncertain. While some believe rising demand will push fees high enough, others warn of a death spiral if fees fail to compensate miners adequately after subsidy phases out.
Q: What is the “security ratio” and why does it matter?
A: The security ratio compares attack cost to network value. A higher ratio means greater protection against economically motivated attacks. Maintaining this ratio is essential as market caps grow.
Q: How does Nervos DAO protect against inflation?
A: Users who deposit CKB into Nervos DAO earn yield from secondary issuance, offsetting inflation effects. This makes long-term holding more attractive and stabilizes monetary policy.
Q: Is proof-of-work still viable long-term?
A: Yes—if properly funded. Both Bitcoin and CKB use PoW for robust decentralization. CKB enhances sustainability by decoupling miner income from transaction volume and linking it to state usage instead.
Bitcoin and CKB represent two distinct philosophies in securing decentralized networks. Bitcoin bets on market-driven fees in a deflationary environment; CKB builds sustainability into its economics through predictable rewards tied to value storage. As both ecosystems evolve, their contrasting approaches will shape the future of blockchain security—one rooted in scarcity of space, the other in resilience through adaptive incentives.