The most relaxing way to lose a coin
Plinko does not ask you for anything. That is its trick. You set a bet, you press drop, and then you are a spectator at a very small physics event. The ball clatters down through the pegs, bouncing left, right, left, left, right, and there is absolutely nothing you can do about any of it. No decisions, no timing, no button to save yourself. Just gravity and noise.
Which should be boring, and instead is completely hypnotic. Playing plinko online is closer to watching a marble run than playing a casino game. Your eyes track the ball, your body leans slightly in the direction you want it to go, and you make a small involuntary sound when it bounces the wrong way at the last row. Everyone does this. Nobody admits it.
It is the pure lizard-brain end of the arcade. Other games make you responsible for your outcome. Plinko takes the responsibility away and gives you the drama for free, which is why it is the one people leave running in a background tab.