I'm 24 and I've given up.
I guess I've become complacent with having no friends (well, I technically have 1, but we rarely see each other). I used to want lots of friends, but after I was abused by 3 different sets of "friends", I've lost all desire to build new friendships. I just don't want to put up with it again.
I'm fine living by myself, and I foresee myself living solo in the future. It's one of those things I've gotten used to.
I don't even have friends at work. I work with a team of people in Europe and I only get to see them once a year. Plus, all the other people who I've gotten along with at work I've met at work-related events... and all those people work at an office location in North Carolina... while I work in Boston.
Like a lot of you guys, I don't drink... which is a "problem" because everyone else my age drinks. It's a social thing.