I’m not sure how this makes money overall though since the reward money has to be balanced at the population level so the platform always comes out ahead. I suspect there’s an element of getting the employee to gamble with their own money with promises to pay that don’t materialise.
They know, and expect, on x% they won't make that $200 back. This scheme structured itself on increasing that x% and being low-volume enough for platforms to not catch on or redefine their acquisition programme.
And if you are that real customer that will provide that y, you're going to sign on the platform with the big bonuses.
There was some forum post by a platform's "loss officer" looking for info on this scheme. They suggested anyone taking part was "money laundering", but money laundering is a pretty broadly worded offence. The responses weren't sympathetic to an online casino complaining about losing money on more signups.