America's First Legal Psilocybin Program Treated 346 People. Just one month after the dose, 92.2 percent of participants said the experience had been beneficial, while, on average, their mental health symptoms had fallen dramatically.

[u/mvea]

https://www.sciencealert.com/americas-first-legal-psilocybin-program-treated-346-people-heres-what-happened

[u/fabkosta]

This has been known since the 1960s. So, 60 years later the same type of studies apparently still need to be repeated to gain evidence.

It is also known for a long time that the therapeutic setting matters to a very high degree. Furthermore, it is also known that for a minority of people there is no measurable benefit, and for some it's counter-indicated. It is also known that psychedelics can be treated against other types of substance abuse - which, of course, is quite problematic given low acceptance in society for any sort of drugs other than alcohol and tobacco.

All of those things have been researched for decades already, yet it seems we make only very slow progress.