There are people who smoke pot to get high, and there are people who use cannabis to open their minds.  That is basically the difference between those it helps and those it harms.

Playing with your mind; going down the rabbit hole... but then you got to get back out.
And if you haven't developed your brain muscle, then it is usually a losing battle.

There are huge piles of similar experiences.  Some consider that proof enough.  But, since we are talking about personal experiences, it is not something that you can just give to someone who hasn't trod the path.  I wish it was as easy as, "here, take this drug,"  because it really is more about the preparation than the drug.