It seems to me that the enjoyment of many kinds of gambling is in the narrative structure. Though simple and fast paced, most games have a rigidly defined story template that gets played through again and again, where the players are characters, and their financial investment is a necessary tool to bind the people to their characters. In effect, the financial stake is the societal glue that lets people role-play with complete strangers.
Consider a hand of blackjack between the dealer and five strangers. The hand has several phases, betting, hand-modification (splitting, hitting, etc), the dealer's play, and the payout. The game is structured on a carefully-evolved interest curve. By placing initial bets, the players tie themselves to the game. They now have a stake in the game, and an interest both in the play, and in the fate of the money they have put in.
Dealing the first card to each player, then the second card to each player, while ostensibly done to further randomize the deck, has the effect of drawing the players attention to each subplot in sequence. Eyes follow the dealer from hand to hand, watching the hand grow, hoping that the ace is matched with a ten-card, whether it's your own hand or your fellow player. By dealing the two cards in separate passes, tension is created for several seconds; long enough for players to hope, cheer, and want, before seeing whether that hope is fulfilled. Dealing two cards to each player, one player at a time, would defeat the drama created by the combination of two cards.
Next, when each player's turn comes to play their hand, every player's attention is focused on their actions. Some players watch to see if the player does the 'right' thing, others place themselves in their shoes, imagining the current player's drama as their own. Once a player is done with their hand, they will still keenly watch what the next players do, as their actions, whether they hit and 'take the dealer's 10' for example, might causally affect the dealer's final outcome, and hence the outcome of every player at the table. It's interesting that the only way players actually affect each other is through the random chance of modifying the deck, by taking cards or not, yet even though the effect is completely random, the causal aspect still draws the other players in to the plight of people who otherwise don't concern them.
After the players finish, the interest curve spikes as the dealer exposes his hole card. It continues at its apex until they bust or stay, and the final outcome is revealed, after which there's the cathartic (and just as importantly, sequential) reckoning, collecting of cards, and collecting or paying off of wagers.
In this cyclic interest curve, of building literal and figurative player investment, laying the foundation for the 'final battle' and the consequent resolution, it's no coincidence that bets are paid and cards are collected in reverse order. The clockwise sweep of creating the story is counterpointed by the counter-clockwise sweep of culminating the story, setting the stage for the next act.
In this fashion, narrative techniques and interest curves are used to form a simple battle between a single player and a dealer into a collective role-playing story.
Important to any role-playing game is that each campaign differs from the last, and blackjack is no exception. the fact that there are scenarios that come up only once ever 10 or 100 hands creates excitement when they do. The time when a player has two eights and splits, and gets another eight and splits again, tripling their initial investment, creates differentiation that in turn creates specific memories of excitement that would otherwise be lost in the homogeneous hand after hand that would otherwise result.
Even more exciting are when these special cases come up in tandem, creating extremely rare and unexpected situations, such as when a player has two aces and the dealer has an ace up and asks who wants insurance.
Regardless of whether the player wins or loses, they still come away enchanted by the narrative, the balance between role-playing a fictional scenario and the very real financial outcome. Add to that the 'shared fate' nature of the game, where in a given hand, it's more likely that several players will win or several players will lose, based on the dealer's hand, rather than a regression towards an evenly distributed mean. This is powerful because it means that, in losing, the player often has the company of other losing players, giving rise to a unified struggle instead of an individual plight. The effect is even stronger in winning, where the shared joy of the table creates individual experiences stronger than if the victory was theirs alone.
This effect is even stronger in craps, where most people win and lose at the same time, except those who are deliberately separating themselves from the fate of the table by taking individual 'off-point' side bets. But craps is a whole other paper.