They are kids and deserve the opportunity to belong. Not every kid has their life figured out at 14 or 15.
Make band available to them, even if its just sitting in the stands because they are on the JV team and can't be at marching rehearsals. Let them be in the parades. Give them a chance. It really should be their choice.
I've seen too many kids get run out of band because they had multiple interests and the director couldn't be bothered to accommodate for them. Kids who made region band in middle school (in tough regions).
And it's mostly marching band that has been the issue. Maybe we should stop forcing kids to be in marching band and make a fall ensemble available. Not every kids wants to march, some just want to play their instrument.