Security Track Record

• •Zero consensus attacks: No successful 51% attack or double-spend on the main chain.
• •Zero protocol exploits: No critical bugs that allowed theft or inflation.
• •Zero rollbacks: The chain has never been reversed or rewritten.
• •Constant attack surface: As the largest, most valuable crypto, Bitcoin is the #1 target. It has survived everything.
• •Bug fixes without disaster: Rare vulnerabilities have been found and patched without loss of funds.
• •Incentive alignment: Attacking Bitcoin is unprofitable—defenders have more to lose than attackers can gain.

51% Attacks

• •Ethereum Classic: Multiple 51% attacks (2019, 2020). Millions stolen via double-spends.
• •Bitcoin Gold: 51% attacked twice (2018, 2020). Exchanges lost funds.
• •Vertcoin, Litecoin Cash, others: Smaller chains regularly attacked.

Smart Contract Exploits

• •The DAO (Ethereum): $50M stolen via reentrancy bug (2016).
• •Poly Network: $611M stolen via cross-chain exploit (2021).
• •Wormhole: $325M stolen in bridge hack (2022).
• •Ronin Bridge: $625M stolen (2022).
• •Hundreds more: DeFi hacks are routine on smart contract platforms.

• •Cross-chain bridges are a massive vulnerability. Billions lost.
• •Examples: Wormhole, Ronin, Poly Network, Harmony Horizon.
• •Problem: Bridges introduce centralization and trust assumptions not present in base-layer Bitcoin.

• •51% attack: Controlling majority hash/stake to rewrite history or double-spend.
• •Double-spend: Spending the same coins twice by reversing a transaction.
• •Reentrancy attack: Exploiting smart contract logic to drain funds multiple times.
• •Bridge: A system for moving tokens between blockchains. High-value targets for hackers.
• •Honeypot: A poorly secured system that attracts attackers (unintentionally or as a trap).
• •Attack surface: All the ways a system can be exploited. Bitcoin's is simple and well-tested.
• •Consensus bug: A flaw in the protocol that allows invalid blocks or transactions.

• •Simplicity: Bitcoin does one thing—secure value transfer. No complex smart contracts = smaller attack surface.
• •Proof of Work: Physical cost makes attacks expensive and obvious. PoS attacks are cheaper and harder to detect.
• •Network effect: Largest hash rate by far. Attacking Bitcoin costs billions.
• •Conservative development: Bitcoin changes slowly. New features are rigorously tested. Altcoins move fast and break things.
• •Incentive alignment: Bitcoin's value is its security. Altcoins often prioritize features and speed.
• •Transparent history: Every transaction ever is auditable. No hidden bugs or backdoors.

• •Smaller networks: Lower hash rate (PoW) or less staked capital (PoS) = easier to attack.
• •Complex code: Smart contracts introduce bugs. Every line of code is a potential vulnerability.
• •Faster iteration: "Move fast and break things" is dangerous for money.
• •Centralization: Many altcoins have admin keys, upgrade mechanisms, or foundation control—single points of failure.
• •Economic attacks: In PoS, wealthy holders or exchanges can take control.
• •Less scrutiny: Fewer eyes reviewing code and security.

• •Mt. Gox, Bitfinex, Coincheck, others—billions stolen.
• •Important distinction: These were exchange failures, not Bitcoin protocol failures.
• •Lesson: "Not your keys, not your coins." Self-custody eliminates this risk.