Fiat does not provide the type of anonymity that crypto does. As long as you're using a site that is reputable you are only battling the house edge.
Fiat casino's doesn't give that anonymity that crypto casinos offer. Gambling with fiat is okay and it's just a matter of choice on where you think is more suitable to you.
It is up to the user that if he wants to use crypto or fiat, there are so many casino which gives it as option to use fiat or crypto but according to my experience it is good to gamble with crypto as for it no one can know how much you have and in case of winning you will not scared of being robbed but you will feel safe about your profit.