The thing about friends is, if you pick friends that are closely associated with one of the other activities in your life, there're going to be fewer conflicts.
So, if you can take-or-leave your bandmates, maybe join a band with people you like even if they don't play as well as the people you don't care for. Bingo, you have friends and your have bass in the same activity.
Same for school. There will be people you like, and people in the same classes, studying for the same exams. Look for people you like who are in the same classes, studying for the same exams. Boom, fewer conflicts.
You never have to say, "Sorry, can't go to the party, I have a band gig" to friends who are in the band. And you never have to say, "Sorry, I can't study, I'm hanging with my friends" to your study circle, if your friends are already in the study circle.