The only game at the table where you get a vote
Most casino games ask nothing of you. You pick a number, you press a button, and the outcome arrives without your involvement. Black jack is the exception. Once the cards are dealt you are handed a genuine decision — sometimes several — and the quality of those decisions changes what happens. Not enough to make you a favourite, but enough that two players at the same casino black jack table with identical cards can end the night in very different places.
That is why the game has outlasted every fad in the building. It rewards attention. It punishes laziness in a way a slot machine never can, because a slot machine cannot be played badly. Black jack can, and most people do, and the gap between playing it badly and playing it correctly is the most interesting thing about it.