Satan/demons as symbols of human evil? I wish!

I've heard some fellow Christians try to explain away Satan/demons as symbols of human evil. I'd like to believe that the Bible was intended to be read that way. However...

‎1.) If the Bible writers meant that, they could easily have said it.

2.) If the demonic=human evil, then the human mind indeed has some paranormal powers.

3.) When I look at how entire cultures can become corrupted-

how the most cultured nation of the early 20th century Germany
can be swayed into genocidal 'eugenics',

how Christendom can be seduced into Crusades, Inquisitions,
Witch Hunts & Pogroms,

how Russia & China can succumb to atheistic collectivist statist tyranny,

how a substantial population of men can degenerate to regard
children as appropriate sexual partners

and a substantial population of women can be pressured into ending
their unborn children's lives-

then I see the Antithesis of what I see when I look at the Origins of
the Cosmos, of Life, of Humanity, of Israel, of Jesus.
For in those latter things, I see Almighty All-Loving Intelligent Design.
In the former things, I see a limited but very palpable intelligent design of Evil.