I don't know about in America, but over here there are loads. And why most annoying? Because declaring someone pretty annoying is pretty much a dick move (oddly most Veggies/Vegans don't ram it down the throats, the "but bacon/steak/etc is amazing!!!!!...etc" are mostly fine apparently. I don't go on about loving tofu etc unless someone asks...
Vegans are perfectly fine if a little vocally sanctimonious on their own. Potheads are annoying but easily ignorable, add them together and you get a sanctimonious annoying person who probably smells like patchouli... terrible but not the worst.
Then you add in crossfit and you have a person who won't stop telling you about their hemp rope made crossfit obstacle course they have in their cruelty free backyard while they silently judge you for eating a burger.
It's the combination of the three.