You prepare for the 9.0 earthquake that can happen once in 500 years because it is a 9.0 earthquake and if you haven't prepared your society is dead, not because you think it will most likely happen in your lifetime.
YAGNI - https://en.wikipedia.org/wiki/You_aren%27t_gonna_need_it
Even regions with few quakes may have a history of large quakes. The New Madrid region (southern Illinois, southeastern Missouri, southwestern Kentucky, northwestern Tennessee, northeastern Arkansas) doesn't experience especially frequent temblors, but when they do occur, they're doozies:
<https://en.wikipedia.org/wiki/1811%E2%80%931812_New_Madrid_e...>
The potential risks of PQC are large enough that preemptive countermeasures seem prudent.
That prep doesn't extend to building standards for higher magnitude quakes.
Appropriate prep is still important for a possible credible threat, even if it is likely to be a rare issue, and the magnitude of that prep differs by personal posture and exposure.
So this isn't preparing for earthquakes, this is preparing for fairies and elves.
"Fairies and elves" suggest it's impossible. It isn't impossible, just very difficult. I'm here in bed conversing with someone on the other side of the world with a hand held device. The would have been "Fairies and elves" 50 years ago.
It's like worrying about reinforcing the barn wall in front of you against komodo dragons when the other three walls of the barn are missing.