When I was around 19 years old I started playing in a pool room that was in a bowling alley, so there was no shortage of low-level scofflaws, but no one I considered "dangerous". (i.e. crazy)
I practiced and got more interested mostly because just wanted to beat my buddies, then I got hooked on the more intoxicating intricacies of the game - english and position play. There's something about the precision of the game that gets in your blood, as well as the feeling you get when you start to rise in status in the room. I had never played anything that was so accessible, so challenging and so much fun all wrapped into one.
There was always some "cheap" gambling going on, but the real treat was watching the occasional road player match up with the best locals. I was fascinated by the head-to-head competition, and amazed by some of the "scores". Fascinating stuff.
Ken