Rapamycin modulates the immune system. I get that he's probably consulting a doctor but can you imagine taking this risk during a pandemic or even in older age? It makes me uncomfortable to play around with these very powerful drugs.
The dosage for longevity is supposed to be low enough that this risk is minimized. Lots of things you do modulate your immune system (including e.g. exercise). It's a risk/reward thing, every time you get into your car you're also taking a longevity risk.
I think there are some proper human trials happening but the jury is still out.
People are still getting nerve damage from too much vitamin B6 in energy drinks and vitamin supplements, and that's a well known and widely taken vitamin. The idea that you can take experimental drugs your entire life at little risk is optimistic.
Surprisingly, many people seem to think that pushing a few random pills into a machine optimized over some million years of evolution will tune it so it works better. Go figure...
Yes, although even for modern medicine curative and preventative strategies are very distinct. Sure, they'll give you pills to compensate for a problem you already have. But there are few meds that protect you against stuff you'll maybe catch in the future. Vaccines and antibiotics are obvious examples, but I'm not aware of many others. The rest of preventative strategies overwhelmingly consists in correcting deficits or excesses (calories, vitamins, sleep, exercise etc.)
