Question

what is the meaning of this quote, "Never before did I realize that mental Illness could have the aspect of power, power. Think of it; perhaps the more insane a man is, the more powerful he could become."

Answer 1

he is seen as having a disability and just like BLM you are given more power based on a "disability" whether it's a mental illness or something else

Answer 2

It doesn't mean "power" in that sense. Essentially, those with mental disabilities typically get treated differently in public. Sometimes people change their entire personality because a mentally disabled person simply walked into the room. He is mentioning the power to make people do that in almost every room he walks into. The more "crazier" you are, the more "power" you have, aka being able to make people change over your presence