Basically the more you lose, the more you can lose, the more you win, the less you can win, simple as that. What the sportsbooks do is the simple trick that if a person starts to gamble their own max and lose a ton, they put that as a sign like "this much this person lost so far" and when it reaches to a point where gambling with a higher max and winning wouldn't really hurt their profit from you, they allow you and because you played so much and lost so much they basically expect the same.

This goes on until like 10 btc if I am not remembering wrong, maybe that was dice I don't now but I know there was a 10 btc bet somewhere here. Of course some people could abuse it and simply just bet the max on the bad odds and lose and when higher one opens they start to win, but many fail and lose even more while trying this .