I'm the same way. I never drank at all until college. I followed the "there's a time and a place for everything and it's called college" motto. Apparently that meant binge drinking 3-4 days a week.

I never drank alone - only at social events. During my senior year, I heard people joke that "it's not alcoholism until after you graduate." Apparently I'm a sucker for cheesy mottos because I followed that one too and went cold turkey as soon as I graduated and haven't drank at all since nor do I have the desire to.

I started talking to an old college friend again recently. He had specifically sought me out looking for new friends because he was recognized he had a substance abuse problem and wanted a sober friend in his life. Apparently I was the only one in our large group of friends that stopped drinking. I remember how I stopped hanging out with them after graduating because all they wanted to do was drink and go to bars which I found boring, unhealthy, and expensive but I kind of assumed they would stop too eventually. That's when I realized that my college friends actually were alcoholics and so are most people apparently.