Lyric discussion by DeLaMer 

Cover art for Geek U.S.A. lyrics by Smashing Pumpkins, The

I think this song is about how a chick turned from being an innocent girl to a more corrupted young adult/drug user. If you read the lyrics thinking like that, you will see what I mean...

I always thought the last line was sarcastic because of how so many young people are ruined by America's drug problem.

My Interpretation

I think you're on the right track. The 'giving herself away' is sexual. How many people have sex hoping to receive love in return.