Do they make more profit than digital banks, CEX exchanges, etc.?
It could be, gambling whether online or offline, is already a billion dollar business.
You just have to look at this forum and see that there are casinos born maybe every month as a business to at least get a piece of that big pie, just a slice and it will be more than enough to make money.
As compare to let's say a crypto exchange, there could be traders around, but it takes skills and technical know how just to make a decent money. Unlike in gambling wherein, some individual from Asia to Africa started to create an account to a online casino and then deposit crypto and starts to play, easy like that and then you have one customer, one potential customer that can get addicted.