"I think there is a 4.3% probability of us getting wiped out by an asteroid"

The mistake here is not the number but the way of saying it: as if this is your guess at the value of a number out there in the world. Better to say

"My subjective probability of an asteroid strike wiping us out is currently 4.3%"

though of course the spurious precision of the ".3" would be more obviously silly in such a context.