I think to properly calculate this, we'd have to work out every possible winning hand in blackjack, then work out the probability for each one individually coming up in a game. There's a more annoying question of how likely you are to win by not busting while others do, which makes the question unanswerable so we'd have to put in stock variable to work through it with.

This is the most I have thought about math in years and I'm surprised I can actually work it out somewhat.