Harry Potter star Daniel Radcliffe gives up drinking

Daniel Radcliffe has given an interview that he has given up drinking at 21 because he has been partying too much since he was 18.  My first impression is BULLSHIT!  What 21-year-old gives up drinking unless he/she was in a bad car wreck, got arrested for domestic violence or had a close relative die of an alcohol-related death?  After further reflection maybe I'm just being cynical and he's a perfect adjusted star that can responsibly handle his millions.  We'll see.