He has a partnership with Stake.com and I assume the majority of losing bets are bankrolled/credited by Stake in exchange for free marketing.
You’re right here but that money is already given to him which means he still lose huge amount as part of his talent fee. It can be considered as regular salary which means he definitely loses his money on this bet.
He is just too rich to feel the pain of losing that’s why it looks like that he lost free money but in reality it’s still a regular loss in gambling since he can have +500K on his bank if only that bet won.