I know. I would become a vegetarian if I could (I'm not giving up cheese and milk though) but it's not possible right now. But people won't change, we have a culture where we think that everything is fine and we can do whatever we want, and that's a problem.
And something that makes this even worse is that there's nowhere to escape to. There's no habitable planets around us. We don't even have an "Oasis" (the virtual reality universe from Ready Player One). This is the world I'm growing up in and I hate it.
Rome wasn't built in a day and climate issues are gaining traction. We don't need everyone to stop tomorrow, but we do need a trend to begin, one that will grow over time. All you can do is worry about youself and maybe those closest to you, and spread the word. Don't avoid doing the right thing just because not all 300 million Americans aren't doing it right now. If you're waiting for everyone else to start first nothing will ever happen.
Also, vegetarians can eat dairy, you're thinking of vegans.