I don't blame only power. This argument would just be like that 'television makes our children disrespectful'
The fact is, television
provides an opportunity for the children to learn profanities and other disrespectful acts, but if the parents use child lock and stuff like that and the children are obedient to their parents and not prone to misbehaving, they won't fall for it. Similarly power provides an opportunity for people to access facilities and leverages they don't deserve, often at expense of others. It just depends on the person's morals and perception.
In all the civilizations you noted, you must see why the dynasties and the like corrupted. Like someone pointed out here, the new leaders and emperors did not have the vision of their forefathers, so they did not have a reason to
not misuse their power. The initial rulers have gone through trials to obtain their country/control, and have established the system themselves, hence hold a strong motivation to maintain it. As the generations come and go the motivation and vigor lessens, as each successive generation is less aware of exactly how valuable the entire society is to them. Hence, eventually, civilizations come to a disastrous end because of pleasure-seeking and unconcerned rulers.
