there's a guy 45 minutes from me that does AMAZING black and grey work, he's tattooed a bunch of my friends with some amazing shit, and has no tattoos himself. He's always been an amazing artist and decided to start tattooing, it seems to have come natural to him. He also grew up in one of the 'hoods so maybe the homeboys encouraged him.
Another guy that did a lot of my work, who is also an amazing artist/painter/tattooer, only has a bunch of scratch from when he was 15. He's now in his 30's and hasn't got anything since being a youngster.
Maybe the fact that both grew up in the hood has something to do with it but no one can take away from the fact that they're great tattooers. Not everyone tattoos to be a part of the 'scene', some just like transferring their art into another media....