What's the meaning of 上 in 你还自恋上了? 你还自恋上了.

What's the meaning of 上 here? Would this sentence be OK without 上? The context is here, in 29:45: https://www.youtube.com/watch?v=k7TaJmcCYpI
Here 上 marks the entry into a state, the state of 自恋.
Without 上 it could also mean that the person entered the state of 自恋, because 了 at the end of a sentence has the meaning of 'change of state'.
But it would be less evident than with 上.