I started shortly before my 19th birthday. Was somewhat of a regular user (i.e. every weekend) for an year or so. Rarely smoked a joint by myself, was always a social thing. After the group disintegrated and everyone went different ways, the few remaining guys and new acquaintances I made were all non-smokers. Usage dropped to nil for a few years. New workplace (been here 18 months) has two regular users, I never turn a joint down. Will get some of my own on occasion. Will also light up on occasion by myself, something I never did previously.
Hell, I actually kind of prefer it alone. Good music, weed and ATOT. Fuck yeah!