It's not batman and Iron man fighting here, its Bruce Wayne and Tony Stark.
Scenario:
Bruce Wayne and Tony Stark are at a conference for rich people, and while there laughing and discussing about how they use all their money to help build awesome suits and technology other than helping the police force or charities. (They know each others identities)
Then Tony says, "Oh Bruce, if only you where as rich as me"
Bruce is annoyed at this and says back "I am richer than you Tony"
This sparks an argument, so who is richer?
lolz.. Stark is a drunk nowadays so Wayne will just offer him a drink and watch as Stark falls down on the floor asleep for several hours, then Wayne will just loot the remaining assets from Stark's companies