Also what are the things that kills such project because even one or two survived for long I don't see many alive till now, they fail easily or turn scam later.
It's a competitive industry. And while it may seem like lots of people like using Bitcoin/crypto inside some kind of bubble, especially on this forum, most people in the world still prefer using fiat, making the vast majority of gambling take place that way.
So it can and does exist and prosper for a bunch of reasons. But there's also a lot of things holding various aspects of it back.