I really became apathetic towards grades this year (jr. year at highschool). I went from ALWAYS having A/B report cards, with mostly A's to getting quite a few C's. I just really saw no point to going insane working all the time, when I can have a bit of fun and enjoy myself, and get a B/C average. I think the trade off is worth it.
Back in high school I took a lot of pride in being balanced. In fact, I was the balancing point of my class. (271st out of 541) Not too high, not too low... right? Just a nice, even, 2.5 GPA. For some reason, my Dad, Mr. High-School-Valedictorian-Bachelor's-Degree-With-Honors-Master's-Degree-From-MIT-In-One-Year was less than impressed.