Hi P.M.!
This is a great question and I will enjoy reading the responses of others.
For myself, I just started down this path and am still educating my self. I watched the Forks over Knives documentary and decided on the vegan way of eating due to high blood pressure and high cholesterol. I am concerned about the factory farming and terrible treatment of animals as well but I admit that I began this for health reasons. I have not yet began to buy vegan clothes, shoes, etc.
As to your post....I don't know that I feel elitist, exactly, by choosing to be vegan. I do sometimes feel embarrassed to be so picky. I try not to be a bother or hassle to anyone while still maintaining my way of eating and I don't make a big deal about it or label myself as such, just to avoid any uncomfortable situations for me or my fellow diners. As you say, being vegan does help the world's food supply in numerous ways, so by choosing to be vegan, I think we are helping the situation which does not lead me to feel elitist.
Again, I'm rather new to this and still sorting out my feelings, perceptions, etc.