I wish more people were vegetarian.
More meat for us.
Seriously though, like stated previously, many people get preachy and self-righteous when they feel that they've found the holy grail. I just laugh at them.
But I have a confrontational side to me as well. If I encounter a preachy vegan at a social gathering where food is present, I'll go out of my way to find some meat, and eat it in their presence, just to ruffle some feathers.
On the other hand, if I see someone eating grains or processed sugar, I don't feel the need to correct them, and I feel sad that they've drunk the kool-aid, so to speak, and usually feel sorry for them.
I mean...if you're truly confident in your way of eating and living, there's no reason to try to convert anyone who has different views. It's too mentally exausting.
If someone asks me about my diet, I'll certainly tell them. Proudly, in fact. The fact that I have good muscle tone, with less than 10% bodyfat at 46 years old is a good testament to our way of eating/living, and it certainly makes them question their own eating habits.