Perhaps I'll get dragged here for this, but It's honestly not just old people, but frankly many on the political right seem to embrace many conspiracy theories. Left isn't immune either, but observationally I think we can agree the "right" seems to peddle more conspiracy theories, and not only Q, but they all seems to have some interconnectedness with people believing multiple and weaving stories to make them fit together. I suppose as you get older and wealthier, you tend to become more "conservative". Its a weird venn diagram of people believing in Q, flat earth, vaxx, etc. I'm talking about the group on the political right that is caught up in culture war issues, instead of economic and fiscal issues.

It all comes down to a lack of critical thinking, misunderstanding the burden of proof and being able to recognize bias. The person/people making the outlandish claim are the ones that need to provide proof, it's not on me to prove people aren't eating pets, it's on those claiming people are eating pets. Saying "do your own research" is not proof lol, and even one half baked example is not "proof". The reason it's so prevalent is that an entire media and propaganda apparatus (Fox News, CNN, etc) exists to push fear and blow up individual scenarios into larger issues than they are, because fear causes emotion, and emotion disrupts critical thinking. It's advertising/marketing 101. Generations of people have now grown up in a confirmation bias echo chamber and bubble, where they peddle only things they already are susceptible to believe because they didn't know how to properly question nor do they understand how burden of proof works. I suppose it boils down to education, and accepting some stranger on 4Chan, or Twitters statements, without scepticism, as facts over peer reviewed research and Occam's Razor.