As`long as the question wasn't stated as "bad" habit, I guess I would say gambling. I look forward to it every day. I don't think it is bad for me, because I always have had it under control, stay well within my means, have good money management and don't let it interfere. I realize it is a marathon, not a sprint and as a result, usually turn a profit at the end of the year. In addition, I don't wager on things that don't add up numerically in my favor, IE: I never play the lottery or slots, and horses and dogs infrequently only for fun.
I guess I understand that if I don't set and keep the above rules for myself, I put myself in danger of possibly having to quit something that I enjoy.
So, perhaps I guess it is more like a hobby, but, nonetheless, it would be very difficult for me to quit.....I enjoy the action very much.