Plagiarism.
Sometimes not even subtle, somewhere is an old depiction of the abrahamic god's chariot being pulled by enslave deities of other religions, in reference to a verse in Deuteronomy "with myriads of holy ones from the south" but I can't even find it in the ocean of slop that is the internet, right now. Sometimes similar depictions popped up in Ezekiel's vision in place of the ophanim. I believe Isaiah's vision included a court ruled over by god which resembles the egyptian and roman pantheons that predate it.
At least two but likely more well known outer deities are depicted as devils in abrahamics: Astaroth and Pan.
This isn't a new phenomenon, either: the chief deity of the Greek pantheon ruled over the chief deity of older religions like Dionysus.
A better question is why humans keep worshipping floods, earthquakes, and eternal tormenters? The answer is fear.