usually at a concert you expect that the last performer is the headliner that folks are actually there to see, but in the indie/local music world that's often not the situation. since shows are booked on off nights during the week or like sunday nights, this means the earlier sets on a bill are the best attended and the bands with a bigger audience may be second or third to play on a bill of four or five acts. this is so folks can see them and end their nights earlier.
it always upsets me when some cool out of town band comes and plays a great show but then all their fans dip leaving the smaller local acts to play to a nearly empty room at the end of the night. sometimes the earlier bands themselves leave too, which is even worse as it's pretty disrespectful for the acts you're sharing a bill with.
in the music world there can sometimes be this toxic narrative of "we all had to play for empty rooms at one point, it's part of the business," but that doesn't have to be the case! stay for the last set and see that local band of awkward 19 year olds, you never know where they'll end up going and how big of an impact early validation can have. to apply this idea broadly, if you ever have the chance to extend a courtesy to others that you wish would have been extended to you in the past, go out of your way to do that for them.