Quantum computing doesn't need to break Bitcoin's consensus to wreck it — it just needs to crack the private keys of lost wallets, including Satoshi's massive stash, flooding the market with coins everyone assumed were gone forever.
Bitcoin's community is structurally slow at hard forks, and even if the network upgraded to post-quantum cryptography, Satoshi can't migrate coins to a new wallet — creating an impossible governance paradox.
The threat isn't science fiction but it's not imminent either: we don't yet know if quantum computers can physically scale large enough to break 256-bit keys.