E-peen isn't always about showing off to others. Sometimes you just want to figuratively admire it for a while in the mirror.
I think they're honestly trying to be better people. And in trying, they become happier with themselves.
But I also think that what they do does not actually make them objectively better, because I have different moral standards than they have.
As a result, the self-satisfaction vegans achieve by adhering to their standard of conduct sounds very much like someone telling me about how they caught all the Pokemon. They may be very proud of their accomplishment, but any interest I show is feigned, purely to spare the other person's feelings.
A fraction of vegans like to proselytize or otherwise promote their voluntary conduct challenge, and I can't stand those guys.