Mostly vegan here. I'm not hard-core, but I try to keep a "clean" diet at home, where I do most of my eating.
Why? Mainly health. Since changing to mostly-vegan, I've lost 12 lbs., feel a whole lot better, and have dropped my bp a few points (it was already in the normal range, but drifting up --now that's stopped
). Reading the China Study and having a dad who survived a double bypass are big motivators as well. My family history is riddled with type2 diabetes and heart disease.