The bouncing ball stops bouncing because of mainly three factors :
1. Friction
2. Gravity
3. Decrease in potential energy
The force of gravity pulls it down, and as the ball falls, its potential energy is converted to kinetic energy. When you drop the ball from a certain height, the potential difference is at its extreme point. When the ball hits the ground, the potential energy naturally decreases, which stops the ball from bouncing after a while.
