You are late to class, for your own reasons, why blame someone else for it? Those few seconds that took for the elevator to stop would not have made the difference for you. It is not their fault that you are late.
(On the other hand, if someone pressed all the buttons just for fun and then exited at 2nd floor, that's a bit annoying, I agree.)
I take the elevator sometimes to the 2nd floor, if it's right there as I'm walking to the stairs. Why not?