Yeah, I'm also a bit worried that the government or anyone with access to a quantum computer or any advanced tech will use it to attack Bitcoin, but I agree that we can prevent or fix it quickly as long as we're prepared.
If that would be the case, BTC wouldn't be the first target on the list, so we should be chill about it, imo.
Before the internet became a public, it was private for military for years undergoing rigorous research and improvement. If there is super computers tomorrow, Bitcoin wouldn't even be the first threat they will look into, there more sophisticated things build and own but government they will try first before they allow public to even have access to it.
Even if there is an update about super computers to tomorrow, things about it will be limited unless they know it's safe for public use to avoid abuse because not only other things will be put at risk, even the governments things might be under some risks too.