Black jack casino basics: it is you against the dealer
Blackjack is not a game about hitting 21. It is a game about ending the hand with a better total than the dealer without going over 21, and those are very different objectives. Plenty of winning hands are won with a total of thirteen, because the dealer drew too many cards and busted. Plenty of hands totalling twenty lose. The number on your cards only matters relative to the number on the dealer’s. Everything else follows from that. Nobody else at the table is your opponent. There is one dealer, one hand to beat, and a fixed set of rules that governs how that dealer plays. Once you internalise that the dealer is a machine following instructions rather than a mind making choices, the whole game becomes far more legible - and far more interesting to play well.
It is also, structurally, one of the closest games to fair that a casino offers - which is not the same as fair. The gap between the player and the house in blackjack is narrow enough that skilled play visibly matters, unlike a slot where your only decision is whether to press the button again. That narrowness is exactly what makes it worth studying, and exactly what makes people overestimate how much of it they can close.