From the point of view of your genes, likely to reproduce and beneficial are exactly the same thing. That's trivially true. Also not particularly interesting even if true: crazy beliefs that get you killed or prevent you from breeding have to spread non-parentally. They don't have to be particularly persuasive or virulent, there just has to be some other mechanism (e.g. state control of education, military discipline, enjoyable but idiotic forms of mass entertainment) to spread them. The prevalence of these means doesn't even have to depend on the ones spreading the memes adopting them for themselves: there can be an economic motive for those who promote them for others to believe crazy things; like there is for drug dealers to sell rather than use heroin.