It's a gamble for those doing it. If you're willing to let them (and I don't see sufficient grounds on which to stop them) then it's pure upside for everyone else, as we learn the results. Very callously speaking, of course. And the upsides are much less when they're not thoroughly and scientifically recording their results, which they're probably not.
The thing is, you're assuming that the methodology employed by people acting as their own guinea pigs will yield useful data. I think this will be a case of GIGO, and the answers we need will eventually come from study, not personal sacrifice.
