Dunno. Think the life-style was forced on them. Playing clubs. I don't think they cultivated the life-style to sing the blues but that's my opinion from the blues singers and players that I've known.Big Bill wasn't a booze hound and later on I don't remember him smoking. Maybe did ealier.
Brownie McGhee was a gentleman and not a hell-raiser by any means. Sonny Terry didn't fit that image either.
Josh White was a nice man. He smoked a lot but didn't drink that much. He was polite and genteel.
These are blues singers who I met occasionally and knew casually.
Leadbelly was a gentleman. Didn't know him but Pete Seeger told me about him.
Frank