So the costume was basically just a kink?

Yep. There was one early Batman series which revealed that his father had once dressed as a bat-man for a costume party. Batman wore the costume when apprehending a criminal who had done something awful to Batdad and the criminal, seeing the costume thought it was Batdad returned to life and panicked falling to his death.¹

⸻

1. Likely inaccurate description of the plot based on 45-year-old memories of reading the story in a library collection.

The underwear worn outside of the pants are a dead giveaway.

Batman’s super power was his bank account(s)

He had superhuman thirst for justice

Justice playing a metaphor for little flying insects in this case, upon which Batman places his hyperfocus. It makes sense.