This simulation of the life cycle of the chaotic belt assumes that asteroids are never replenished. In reality, the Poptorian system undergoes constant asteroid flybys and periodic bombardments, like Niesre but to a lesser extent, with fewer oncoming objects. Those that pass very close to Poptor are captured and put in orbit in the chaotic belt.
The chaotic belt bombards the inner four moons(those being Nierlon, Arnso, Gibrear, and Trintros) while leaving Obrone out of impact risk until the next bombardment event. Overall, Trans-Poptorian objects fly into the system to replenish it, and are eventually ejected or destroyed, in an eternal cycle(eternal isn't true since there are a limited amount of Trans-Poptorian asteroids, but it will take about 3-5 billion years for them to be depleted.
*fixed vertical gravity error*