I’m no astrophysicist but I think most objects actually do either have a decaying orbit or an expanding one, but they’re just doing it really slowly.

Also consider the fact that we’re observing just the tiniest sliver of the history and visible area of the universe. So all the objects that would decay quickly and crash into their central mass either did already or will only come into our visible range later (and briefly). What were left with is what seems like a huge proportion of objects in stable orbits.