I think when it comes to a network like bitcoin you have to always assume the worst and assume that a bad actor with enough resources will try to break bitcoin. What that actually looks like, I don't know.

I remember hearing from someone about moving bitcoin to quantum resistant addresses (way over my pay grade) or something and the shear amount of time it would take to move all bitcoin with the limited block space means that an upgrade of that type would take many many years.

Again, over my head but I would think that instead of discussing how quantum isn't a realistic threat right now we should address what to do if it is in 10+ years.