The crux of the ending is that Cobb doesn't stick around to watch the top spin because he does not actually care if it falls or not. He's home and reunited with his children, exactly where he wants to be, and he's not about to go anywhere, no matter what the totem has to say about the situation.

How does inception really end?

Throughout the film, Dom tries to come to grips with his wife's death, the nature of reality, and where he truly belongs. At the end of the film, Dom is reunited with his children; he is finally happy.

Is Cobb still dreaming at the end of Inception?

Cobb's totem is a spinning top, which will continue turning forever in a dream, and only fall naturally in the real world. Cobb makes a habit of spinning the totem following each risky adventure, but when he gets off the plane after a successful mission and begins the test, he's quickly drawn away by his children.