All known bodies of the space rotate around their axis. For example, Earth completes a full rotation cycle in about 24 hours. However, the axial tilt seems to be constant, even though it changes a little bit over a long (in comparison with rotational period) time.
What causes the tilt to stop getting smaller or bigger after some limit?
Why is the axial tilt variation so slow compared to the rotation?
One article regarding the 177.3° axial tilt of Venus suggests that "it’s possible that Venus was knocked upside down by a massive impact early in its history". Let's assume that the impact happened. What caused Venus to stop after 177.3°?
Why doesn't our South pole appear in the equator after some time, and after some more become the North pole?