How to be a quack doctor in DC without getting beaten to death by Batman

After traveling through time, Wayne found himself a bankrupt rich man in Gotham, running a shabby clinic. Fortunately, there was a comfort gift gold finger system.
However, Wayne found that life was even worse:
the clinic sign was used as a target by gangsters, and AK bullets were in short supply than medical equipment.
He treated the Flash’s athlete’s foot and was almost sent to a wheelchair by the Reverse Flash.
He lied to Superman as an old Chinese doctor and said that the other party was infertile, but was hung on a street lamp by Lex Luthor and labeled as a charlatan.
The only VIP customer was Bruce Wayne who came to collect debts, and the souvenir left was a shuttle of bat darts.
The bastard system made nine out of ten draws useless, and the only chance to get equipment was when performing hemorrhoid surgery on the Joker.
And Wayne was stunned when he saw the new task of the system:
[Medical Cooperation Task: Let Darkseid sign the “Cosmic Medical Insurance Agreement”]
“Help, I’m just a mediocre doctor who wants to get rich by drawing lots!”