Thank you. Good read

Thanks for explaining this stuff in a way a "hobby geek" can grasp - so helpful. Side question: I saw Rusty's great script restoration preso last year and it sounded like a great plan to me - do you see that as a positive long term path forward if it can be implemented?

Should we get worried?

Yes, sell all your btc

For those of you who have not read Mr. Lopp's original article, here is a summary. The Cliff Notes version if you will - Assumptions and Guarantees - Bitcoin assumes that the majority of miners act honestly, incentivized by block rewards. - Full nodes guarantee several facts: no monetary inflation beyond defined limits, no unauthorized spending, and no double-spending. Thermodynamic Security - Once a transaction is confirmed in a block, reversing it requires significant energy. An attacker needs over 50% of the network's computational power to reverse transactions. - The cost to rewrite Bitcoin’s entire blockchain is prohibitively high (around $277 million), making such attacks impractical. Sybil Resistance - Bitcoin nodes are resistant to Sybil attacks, where attackers create multiple fake peers. A single honest connection allows a node to disregard false information from dishonest peers. Consensus Properties - Bitcoin achieves eventual consensus, exponential convergence of forks, liveness (new blocks added regularly), correctness (valid transactions only), and fairness (mining proportional to computational power). Checkpoints and Bootstrapping - Hard-coded checkpoints ensure a common history for new nodes, preventing Sybil attacks during initial sync. - Bitcoin uses DNS seeds for bootstrapping, requiring trust in at least one honest seed or node. SPV Clients vs. Full Nodes - Simplified Payment Verification (SPV) clients download block headers, reducing resource needs but assuming valid transactions. SPV is less secure than full nodes, which verify all consensus rules. - Running a full node offers superior security with minimal trust assumptions. Security Considerations - Full nodes require trusting hardware and software to some extent, though methods exist for verifying software integrity. - Miner concentration poses risks, but incentives align against malicious behavior due to capital investment and network monitoring. Infrastructure Options - Alternatives like mobile wallets or SPV with custom configurations can balance security and convenience. Proxies combining third-party services with local verification offer hybrid models. Run a Full Node Already Running a full node provides the highest level of security for Bitcoin users, minimizing trust assumptions and ensuring financial sovereignty at minimal cost.

"The cost to rewrite Bitcoin's entire blockchain is prohibitively high (around $277 million)..." That seens to me extremely low. When you take into account the difficulty of buying so many hardware and other factors, it's probably way higher, I assume.

I believe the original article was written 7 years ago, it’s highly likely that the cost listed is no longer accurate.

It’s fascinating to see how Bitcoin’s development has evolved over the past 8 years since you explained its security model and the role of hardcoded block checkpoints. The upcoming removal of those checkpoints in Bitcoin Core must feel like a significant milestone—both in terms of the tech maturing and the confidence in its decentralized consensus mechanism. What do you think this shift says about where Bitcoin is heading, especially regarding trust in the network and its security assumptions?