I find it exaggerated for a whole month of gambling and you're not winning even once, otherwise that casino is indeed fishy, if he's telling the truth. But one thing is for sure, no casinos were built and design to favor the bettors. It would always be either an honest provably fair casino or designed for them to always have the edge.
No, unfortunately, the OP hasn't mentioned or dropped some names of those websites that he is saying and claimed that no one was actually winning in the crypto casino after spectating the websites for a whole month. OP just mentioned that he tried three websites and actually, I'm not sure which casino he's referring into because there's literally few dozens of crypto casinos out there.