How was Hydra formed? How did it get so many followers and last for so long they are still a threat today?

How is fascism still so popular in real life today? Why does hitler still have followers to this day?

Basically the answer(s) to those questions is the same as the one you're looking for.

Also, add literal superpowers and things get amplified exponentially.

Someone cut off one head, and two more sprung up in its place.

Exponential growth is a bitch.