I was playing a Spanish 21 game with a $1 progressive jackpot. I was ignoring the side bets. Then, I got a pair of Aces v. a dealer Ace. And, the dealer had an Ace down! The progressive jackpot was over $9,000. So, it got me thinking, at some point that $1 jackpot is +EV. There is a 100% payout for four-of-a-kind (your first two cards match the dealer's first two cards). There are smaller payouts as well. Just thinking about the 100% payout on four-of-a-kind, at what point is that +EV for a $1 bet?