The bitcoin subreddit won't answer me. Why should anyone trust crypto which isn't currently quantum-resistant? What if the community is too late to hard fork or switch to a quantum-resistant encryption algorithm? Is that possible/would that matter?

I keep getting downvoted and having my posts deleted on /r/bitcoin despite the fact that no one has given me a good answer. Most basically answer "it won't happen for a very long time so it doesn't matter". To that I say "how do you know what the classified world has up their sleeve?" (hint: you don't). I also want to know if anything could be done retroactively if the bitcoin network procrastinated too long on updating, which I am convinced it will (and no one has answered me on that either).

Final problem: even if something can be done retroactively, what if some evil genius keeps inventing new algorithms that work on a quantum computer that can crack any hard-forked quantum-resistant encryption algorithm? Would it just be a case of cat and mouse with each hard fork being the result of a big case of double-spending?