I was vegan for 8 years, so if someone were to ask me I'd say "been there, done that.". I believe the reason someone would ask that question is the logical fallacy that you are quitting drinking because you are going on a dietary health kick and being a vegan is considered by some the extreme end of that scale. I suppose some give up alcohol for the same reason they became vegan, but the two are not contingent on one another.