On the other hand, I can imagine that if one has fallen into the conspiracy rabbit hole, not done anything to reduce risk like getting vaccines or masking, or even going out of your way to avoid taking those precautions, then losing some family members to covid might make doing those mental gymnastics much easier. Because if one admitted one was wrong after such a thing happened, that would also mean accepting the idea that one might be partially responsible for the deaths of one's own family members, and that is such an awful truth to accept that I can easily imagine someone desperately clinging to any belief that would make it not so, regardless of how absurd it was. Indeed, the longer one hangs on to it afterwards, the worse one's actions look once you abandon the conspiracy theory, and so the motivation to cling to that belief no matter the evidence just would get stronger.