A general-purpose quantum computer of sufficient qubits would be capable of attacking public key cryptography and therefore Bitcoin. However, there are two issues with that.

First, quantum attacks only work against Bitcoin addresses that have been re-used (hence exposing the public key behind it). Any address that hasn't been spent from yet (i.e. the public key is not public yet) cannot be attacked. That leaves only a little room for quantum computers to attack Bitcoin. But if such attacks begin, Bitcoin could fork to use a post-quantum cryptography signature algorithm (of which a few exist).

Second, those kind of quantum computers are at best decades away from being built. Between now and then, Bitcoin will experience more pressing problems (e.g. a global depression).

Moreover, it is likely that quantum computer research will go the same route that AI research did in the late 80s. The US government is the primary funder of quantum computer research and was the primary funder of AI until the 90s. When the US gave up on AI, the entire field went into a winter for a decade; research into general-purpose AI is now uncommon. Research into general-purpose quantum computers will likely go the same route: the US will likely cut funding and people will abandon quantum computer research for a short while and then research will re-focus on special-purpose applications.

Regarding AI: despite ~40 years of US government investment in AI research, the most advanced AI they made was a sophisticated logistics program.[0] AI researchers spent those 40 years trying to make general-purpose AI, yet they only ever made special-purpose AIs. Nowadays, the most advanced AIs are all special-purpose (e.g. Google Search, image generation, etc).

[0] = https://en.wikipedia.org/wiki/Dynamic_Analysis_and_Replanning_Tool