Hi Andreas, I don't know who you are, but since you made a polite post here, I will try to respond and explain. I skimmed the articles, they are long. Modern writers seem to try to compensate for their lack of insight with excess verbiage. Elliot was a better writer than the authors of these articles, and he had considerably more insight into human nature.
Hopefully you have seen the movie Idiocracy
. Think of the courtroom scene where the main character is ridiculed for speaking proper English. Idiocracy is a caricature of modern America, and a very accurate one. The average American today is an ignorant, uncivilized, self-righteous moron. In the courtroom scene of Idiocracy we just see a glimpse of ridicule. But imagine being subjected to it for years.
The ridicule that a civilized person experiences in America isn't so overt. Often it is subtle, like just being looked down on or being treated with mild disgust. The more perceptive one is about other people, the more one sees. Elliot was quite perceptive. So how does a civilized person react to this? At first, it is hard to believe that people are actually like this. After all, Elliot is human and so he would naturally assume that some other people are like him. In particular, like any man, he wants a girlfriend. He isn't looking for general acceptance by all women or all of society, he just wants ONE girlfriend, just one woman who isn't at the pathetically low uncivilized level of modern America. Of course he doesn't find such a woman because she doesn't exist. All women who are part of American culture are human garbage. So what is he to make of this in his own mind? First, it is patently obvious to him that he is far superior to everyone around him. This isn't narcissism, this is fact. He would much prefer that this wasn't true, that there were a few other civilized people around him who he could relate to. But it is true. In American culture, a civilized intelligent man is truly alone.
As I explained elsewhere, Elliot's problem was that he was emotionally invested in American culture. He should have rejected it and looked for people he could relate to elsewhere. I think you meant "sympathy" where you wrote "empathy". Elliot did realize that Americans deserve zero sympathy, even negative sympathy. I fully agree with Elliot on this. But Elliot should have used this lack of sympathy to just turn his back on American culture, and to exploit it (primarily financially) for this own gain.
Elliot wasn't crazy, he was just misguided. He didn't realize that there are alternatives to American culture. If there really weren't any alternatives, if the whole world was like mainstream America, then in fact what he did would make perfect sense.