It's Batman, some of his rogues gallery would do that regardless of any money involved.
Joker: for the lols
Two Face: coin landed tails
Ra's Al Ghul: you're part of his next depopulation project
Riddler: you failed to answer a riddle, Jigsaw style from Saw
Penguin: probably one of the few that is motivated by money for moneys sake, but still psychotic enough to snap and take it out on a room
Poison Ivy: you stepped on a plant
Mr. Freeze: whether or not his latest experiment is working or not and whether you stand in the way of it or not
Kite-Man: hell, yeah.
Killer Croc: wants to eat you
King Shark: wants to eat you
Bane: probably the widest range of reasons but unlikely to ever be because of money
And the various henchmen for all of those are often enough more than happy to be violent for the sake of violence, otherwise they'd probably pick other jobs for money that didn't involve carrying enough firepower to level buildings.
“Poor people” as in, you know, hardcore criminals that will shoot and kill for $20 in your wallet…
It's Batman, some of his rogues gallery would do that regardless of any money involved.
Joker: for the lols
Two Face: coin landed tails
Ra's Al Ghul: you're part of his next depopulation project
Riddler: you failed to answer a riddle, Jigsaw style from Saw
Penguin: probably one of the few that is motivated by money for moneys sake, but still psychotic enough to snap and take it out on a room
Poison Ivy: you stepped on a plant
Mr. Freeze: whether or not his latest experiment is working or not and whether you stand in the way of it or not
Kite-Man: hell, yeah.
Killer Croc: wants to eat you
King Shark: wants to eat you
Bane: probably the widest range of reasons but unlikely to ever be because of money
And the various henchmen for all of those are often enough more than happy to be violent for the sake of violence, otherwise they'd probably pick other jobs for money that didn't involve carrying enough firepower to level buildings.