I've had militant vegan neighbours when I was a student. I don't know how they did it, but they found ways of turning every conversation about them and their "superior" life choices.

Then there are the vegans I sometimes meet during my summer work ours; the ones standing on the street and bothering everyone walking past them in a very persistent manner. Like a jehova's witness.

I'm not saying every vegan is like this. I think I've met more vegans that didn't rub it in everyone's face than ones that did. But consider yourself lucky that you haven't met anyone like that in twenty years.