It's not *new* they have just tagged a name on it from pop culture..for years some of the mentally ill have thought the CIA to aliens have been controlling or monitoring their lives..we all joke about mental illness being a made up issue with fake symptoms etc. but this is just a new name for something that has been around for years and not the first time I have heard of someone thinking this way LONG before said shows ever come to light.
So they are not *delusional* they are mentally ill..so they maybe delusional in a way,but not in the way you are thinking. Different delusional.

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"Cast upon this globe without physical strength or innate ideas, incapable in himself of obeying fundamental laws of this nature which call him to the supreme place in the universe, it is only in the heart of society that man can attain the pre-eminent position which is his natural destiny. Without the aide of civilization he would be one of the feeblest and least intelligent of animals.."
Jean-Marc-Gaspard Itard