Nah. Stood back and thought about it, and realized that
1. She pisses me off and doesn't seem to need/want me for anything
2. She is obviously going to go get shitfaced and hung over to negate anxiety (also, because it's cool, bro) no matter what I say
3. She is obviously going to go bonkers with the boyfriend no matter what I say
4. A little alcohol-caused brain damage won't really matter that much at this point, because she's apparently already decided that she doesn't want to do anything particularly extravagant with herself intellectually--so there's no real reason for me to meddle around. She's got brains to spare for secretarial/office work or housewifery, which sounds like it may be what she actually wants to do.
^ That's the really important one. I'm not going to claim that I know how to win at life and that as such I should be able to tell her what her goals are. If she's going to optimize for short-term happiness, that's her problem.
5. She may need to run herself into the ground so that she learns to take other people's advice. I know I did.
Meh. I guess it is pretty infeasible sometimes to protect people you love from what they want to do with themselves. It seems more and more likely that I should stop shunning people due to life choices I disagree with, so long as I'm not the one who winds up needing to clean their mess.