A highly dangerous drug, and all the more dangerous because it is subtle.
My experiences with people who used it extensively are entirely negative - major personality changes - empty and unfounded hubris, hostile impatience, heightened aggressiveness, delusional paranoia, etc, and then there's a bad side, too.
The was a famous black comedian, now in disgrace, who did a solo routine in which he delivered both sides of a conversation between two people:
A: So like, why do you do cocaine?
B: Because it intensifies your personality.
A: Yeah, but what if you're an a--hole?