If you are familiar with this American artiste you would know that he is a big time gambler or you can just say he is addicted. People are amazed he won such an amount of money in a single day but I'm not because there's a high chance that he has lost up to that amount or perhaps more than that if you calculate his losses combined. This win might actually be a way to lure people into gambling, it's very possible that the casino allowed it to happen for promotion purposes. It could be a way of advertising their casino what do you think about that? It's just a random thought, It's also very possible that he just got lucky.
If you really understand what was going on you would realize these losses are all an illusion and he is in fact in an advertising partnership with them. He has a massive fan base of impressionable followers who want to copy what he is doing, Stake is notorious for using any kind of marketing they think will increase their player base and he is probably one of the biggest deals they've ever managed to score. This 40 million sounds like a lot, but it's nothing compared to the publicity he brings this casino and has probably made hundreds of millions by drawing players over or creating new gamblers. Besides all that, in this partnership Stake can make his account balance look like anything without him ever depositing or risking a cent of his own money.