Counter-anecdote: I've experimented with this stuff extensively in various settings and have known many other people who did, and in my experience it's unequivocally bullshit. Here's what happens. First, any given trip alleviates depression for about a month or two. That makes sense to me in a sense that the word "trip" isn't a coincidence-- a really fun intense vacation in a foreign country also alleviates depressio…
I read a lot of experiences from people who went down both the paths you're talking about so I just avoided them. Rather than not using and considering it inevitable that for years I would be using psychadelics in a degenerate way. I approached them with the mindset that they are a tool to look at problems from a different perspective and accelerate certain forms of thinking. However this tool, independant of actual self-improvement, was not only useless but self-destructive.
I ended up having subjectively worse mental health after the psychadelics. Although the psychadelics were a desperation attempt in the first place so take this with a grain of salt. At the same time my life OBJECTIVELY became much better. Better diet, more exercise, more social life, stronger, more cash, all that jazz. I basically turned around a situation where I was completely trapped in poverty and despair to one where by a good number of measures I was pretty successful. So I do find it interesting to read about how people who take psychadelics are all deluded into thinking they're doing well when they're doing awfully. Since that's precisely the opposite of what I experienced.