In order for evil to succeed you have to destroy free-will, as the purpose of all abuse is to force a decision on someone that is in the disadvantage of the victim.
Because the purpose of free-will is self preservation, it literally makes it impossible to create life without free-will, or to destroy it in already existing life, because it means creating life that can self-preserve. The same way like creating an animal without a mouth or way to feed himself, it will just starve to death and it will be of no use to you, because you can't exploit it.
This is why even with genetic modification or AI in theory it still has to be impossible to create the perfect slave that just does whatever you tell them to do and never rebel against you.
A good comparison would be domesticated animals, you can make it more docile, breed traits that are productive to humans or harmless for the most part, but the natural part that you are suppressing is still there you can't eliminate it, without killing the animal. It is enough for that animal to spend a few weeks in a normal natural environment and it will become completely untamable like feral cats, or horses that roam and join wild herds.
This makes the task of evil people an impossible one because in order to profit from their evil deeds they have to protect the very own thing that has the potential to set the victim free and turn against them.
The evil can win battles, but never the war, because autonomy and free-will are intrinsic parts of life.
The good news is that we never lost our autonomy and free-will because it is impossible, we simply gotten confused about that. The only thing you can do is to confuse people that they have no choice in regards with some thing or that they are making they're own decisions when in fact it is a very controlled and forced decision.
To reverse the damage of evil it is just a little bit more complicate than, for the abused individual to recognize all the choices he has in the moment and that he is always free.
