See also, the DAO hack.

Yeah that's a great example. I think sometimes people take "code is law" too seriously, when it is clear to me the code is just a deterministic way to form a consensus that works 99% of the time and the other 1% you get forking.

What Ethereum did after DAO was way more sinister. At least with the Bitcoin "roll-back" there were no transactions reversed. The miners just got together and started mining from a previous point in the Blockchain, and eventually the new chain had more work done and was validly accepted by even outdated nodes. Ethereum just went ahead and added this to their protocol: "ummm this transaction stands reversed, you don't need to verify signature for this particular transaction". This blot will stay in the protocol for ever.

Bitcoin (et al) is/are not fully decentralized in the sense that a core development team actively maintains and proposes changes, even minimal ones. While it's true that major updates require broad consensus and may be rejected by nodes if controversial, we should acknowledge that certain points of centralization exist, particularly around development and decision making. These often overlooked aspects now carry more financial consequences, especially as Bitcoin becomes more intertwined with regulated financial instruments and political power.

For example, now, many L2s around Bitcoin are fully depending , and influencing on a future change: enabling again the OP_CAT opcode [1].

[1] https://github.com/sCrypt-Inc/awesome-op-cat

Bitcoin can be forked, and in fact has been. You didn't mention mining centralization, which is another avenue.

One of the biggest points of failure I can see happening is self hosted node packaged software services like umbrel. Where they are just updating your node for you.