The illusion of ego dissolution maybe, I mean this is difficult to quantify, but we do have research that shows the brain changes experienced meditators get dont happen to psychedelic users. Every psychedelic user is back to being an egotist quickly in my experience while the meditators I know seem far less egotist and are always advancing.
I don't think there are shortcuts to enlightenment and drug culture posturing is just fraudulent to me, or at best, a cheap and ugly temporary fix that ultimately distracts people from the proper path. That said, it does push some people to the right path, so it can't be all bad. The larger issue is that a lot of people have latent schizophrenia and its impossible to know if you do and drugs can set it off. Its not worth the risk imo.
This happened to someone close to me and it was difficult and heartbreaking.