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No one knows how many BTCs this man has and what year he acquired them. Maybe he is not a gambler but just decided to try his luck in the hope to increase his capital. There were times that I lost all my money hoping for luck but the luck did not accompany me. It is quite possible that we see a similar situation here.
You are right on this one on where people do have this kind of behavior on betting then its likely this guy are those who had invested or mined into those early days of Bitcoin because if you had invested or accumulated on later years then you wont really be having this kind of spending.
Even if this guy has accumulated a large sum of bitcoins during the early adoption and mining stage, it would be crazy to risk all his earnings into a single bet. Probably this guy is a millionaire or billionaire who doesn't bother losing money, since there is much more to spend from where it comes.
Gambling is never a good idea in means on raising up your money because most likely you would really be ending up on the opposite thing which gambling is for entertainment nothingless.
Dont expect that it could make you rich even more because chances on being poor is high. lol
We have to be aware to the fact gambling is going to be profitable only for a very small percentage of lucky players, while everyone else is going to lose their bets, so the few winners and the house can make profit. At same time, there are no huge victory and fame without high risks, and that is what many gamblers are looking for, especially those who can afford insane bets sizes, like the one presented on this thread.