Yep, drugs can be dangerous, it cannot be understated enough. I've experienced both sides of the coin. For me, the profound thing that drugs has done is to provide a standard form of measurement within my own subjective experience. I now rate every euphoric thing as 10% mdma-intense, 50% mdma-intense and so on. What blew my mind is that I have experienced certain sober euphoric experiences that were much more intense than mdma (e.g. doing a meditation retreat and during that retreat I sometimes found myself mindfully in the zone, that was much more intense).
The same goes for the existentialism part when it comes to psychedelics. I have a new perspective on having children while not having had children myself. But the whole idea of that they are little reflections of you and your girlfriend bundled up in one which makes huge emotional impact on you, that makes a lot more sense now.
Or another one: sometimes I act like I'm on mdma (while I'm sober and reasonable enough), those days are a blast!
How drugs screwed me over: 6 months to a year of almost losing touch with reality (constantly needing to stay rational, so that I wouldn't lose myself) or being a bit too paranoid for a few months (just a bit). Or wanting to jump out of the window while on shrooms (I had countermeasures in place, never thought I needed them).
So yea it's dangerous stuff. You can learn something amazing from them, but you can also learn a lot from intense exercise drills (if you treat them like a drug-like experience), or meditation, or dancing, or singing, or falling in love, or making friends, or talking with friends.
Goodluck and have fun with life :)