The lion king, is about an oppressive regime and their "in group" that live in the pride lands.
The hyenas are an oppressed underclass that is easily radicalized by the promise of power over their oppressors. The whole situation could have been avoided easily, simply by Mufassa raising up the hyenas to equality with the rest of the animals.
The hyenas clearly had enough power to topple the pride lands, since they did it.