“Power” is not a supernatural corrupting force. Evil does not exist, there is no such thing as a supernatural force that guides the actions of people. What you are confusing is the profit motive within capitalism incentivizing rule bending and corruption, as well as the continuation of class struggle into socialism requiring constant vigilance against capitalist restoration.

As for the majority saying life is better post-socialism, this is wrong. The majority of people that lived in the Soviet Union want it back. Additionally, over 90% of Chinese citizens support their system. In reality, socialism delivers far better democratic results, because the working classes are in control:

We will always need to transition between capitalism and communism with socialism. You cannot collectivize all production and distribution overnight, you cannot wither the state overnight, you cannot eliminate classes overnight, and you cannot take people from capitalism to communism mentally overnight. This is an impossibility.