Weird thing is, he is not on the top 10 list, which means dude didn't wagered much enough to go to top 10 and still won or maybe he is one of the hidden ones but if he was hidden than we wouldn't see his big win, which means its unlikely that he became hidden later on, he probably didn't wagered much neither before nor after the big win, that is a huge profit in any calculation ever.
Usually, winners of the contests are those gamblers who wager on small odds with high probabilities. As the total wagring amount determine the winners, in this way they can play for a long time and increase their wagring volume. They try to play with low risk and lose as little as possible.
Common technique I shall say when it comes to wagering contest but this would only fit out for those who do had tend to deposit small balances
but if a certain big bettor or whale would tend to join up then those wagered amount you had reached will just be sweep out on few bet of theirs.
Lucky thing if they didn't have any interest to join in.
high probabilities bets i.e. 98% winchance and such are terrible , they only work as a means to increase your wager
it is incredibly hard to make profit betting 1.01x since if you win you only get 1/100 of what you bet , but you lose every 50 bets on average
because of the house edge , this kind of bets is when the casino is making money , usually
but if you have a big bank you certainly have higher chances to win a wagering contest