Nobody dangles a carrot of earning money in front of potential FOSS developers. Nobody goes into FOSS thinking they’re going to get a big payout.
FOSS is not pay-to-play. There’s no equivalent to Robux for FOSS developers.
FOSS developers are consenting adults who volunteer their time for freely distributed software projects, not kids creating content for a video game company that charges them for access and then makes a profit from their work.