Is There a Critical Ingredient for Meltdown?

There have been a lot of authoritarian regimes which have melted down within some months of seeming reasonably secure. The kind of meltdown that I'm talking about isn't led by anybody necessarily or isn't a choice of something else. It's just a failure of the machine that exists to the point where it gets destabilized and the leader. And ultimate control changes hands. So yeah, this is to have a well-organized opposition, a civil society, an attractive leader in the wings would certainly help with the creation of a democratic successor regime.