lol, he didn't win any bonus at UFC 300, the winner from the bonus was Max Holloway. And holloway not only wins 1 bonus, but he also wins 2 bonuses for a total of 600k. Moicano knows Max won those bonuses playing clean and he even sent a message to Max saying "Huge congratulations to Max Holloway... 600k bonus he absolutely deserves!!!".
So, if he wants a 300k bonus in Bitcoin, first he needs to win that bonus.
The man just used the opportunity to promote Bitcoin a little, and if one day he wins the bonus, he clearly wrote how he wants to be paid. However, I think it's much smarter to invest in Bitcoin yourself without raising a lot of dust - because if you get $300k, isn't it easy to transfer that amount to an exchange and buy BTC?
From a security perspective, it is not wise to tell anyone that you are your own bank, because thieves rob banks, especially if they are located in private buildings such as houses or apartments. However, perhaps the man is counting on the fact that his martial arts can deter the bad guys with such intentions💪