[User23]

This is the concept of ergodicity. The fun fact is that even if casinos offered a game with 50% odds players without unlimited bankrolls would still always bust eventually[1].

It's similar to why betting $1 to make $1 million at million to one odds is a smart bet, but betting $1 million to make $1 at the equivalent odds isn't, unless you have an unlimited bankroll.

[1] If they use the Kelly criterion they won't bust hard, but they'll still lose most of their bankroll.

[klipt]

But real world casinos also have limited bankrolls and can go bust given 50% odds. Which is why they never offer 50% odds.

[buboard]

thaat's only because they have "chosen" to not allow players with negative balances or margins.