The same way that not acknowledging that some accepted-as-benign substances can bring about mental health crises, overweighting of personal risks can cause weight-bearing pillars of modern society to crumble.
Saying vaccines are well studied is like saying drugs are well studied, it's a category error. You can't study vaccines as a whole, and the quality of studies of specific cases vary wildly. As a consequence, common psychedelics are probably much better studied than some common vaccines. LSD in 2025 is the same substance as it was when it first became available, as far as I know, and there's lots of research into its effects. Compare that to the COVID vaccines which weren't even the same substance from trial to deployment, as the manufacturing process was changed completely. The trials were done on vaccine made using a very slow, non-scalable and expensive process that yielded a very pure result. The stuff people actually took was made using a totally different process designed for cheap mass manufacture. That second process had problems, leading to DNA contamination in some batches, which seems to explain why injury effect reports clustered by batch serial number.
All this was heavily suppressed for a long time (e.g. by rules forbidding study of vaccine vials), but has been coming out over the past year or so as the initial findings were confirmed. Research into psychedelics at least doesn't have that kind of problem, I think?
Psychoactives and homeopathy have plenty of capacity to be harmful and aren’t necessarily anywhere near as well studied, but at least their effects are more bounded to the individual. (This does not however justify pushing them blindly.)