How does the cloud of debris stick around? For context, I've played Kerbal so I know a bit about orbits but not much. My intuition is that the velocities invol

How does the cloud of debris stick around? For context, I've played Kerbal so I know a bit about orbits but not much. My intuition is that the velocities involved in being in orbit in the first place are so big (7 kilometers per second according to a quick search) that the orbit of the debris won't be substantially different, so it will still decay. Even if you give enormous kicks to the debris, most of it will end up with orbits intersecting the earth. The ones that don't will still intersect the original collision location, and so still experience decay during that part of their orbit. Basically, to change your orbit you need to boost once to push the other side of the orbit out and then again at the other side to push the original side out. A collision can only give one of the boosts, and so is sort of inherently bad at moving the orbit.