why do some crypto casinos offer way better odds on specific games

Been spinning my wheels on this for a while. Some crypto casinos throw out wild odds boosts or low house edge on one or two games, sometimes only in certain versions of slots or roulette. Like you’ll see European roulette with better than normal payouts, or certain crash games acting like money printers for a week. I get the promo angle, but sometimes it feels like there's no catch, which sets off my “what’s the angle here” alarm. Do they just want to hook us with some cheap thrills and hope we stick around for the long haul, or is there something deeper, like those games being less volatile so the site’s safe even with better odds?

Feels like I’m missing something in the fine print, or maybe there’s a behind-the-scenes thing I don’t know about. Anyone ever actually take a decent win off one of these “super fair” games and get paid out? Or is there some kind of hidden tradeoff I’m not seeing?