Robert Nozick wrote, a while back, an article with this title. It’s an odd piece, and its essential answer to the titular question is, I think,something like this:
“Intellectuals – those whose job is to move words around a lot, whether academics, media-types, novelists, etc. – are usually people who did relatively well in school and relatively less well in wider society. This makes them resent market-society for frustrating the expectations they had built up; they want to make all of society like a school, where professor Lenin gives out gold stars not to the industrialists and bankers but to the best intellectuals.”
The primary problem with this piece is, of course, that it poses a question and then studiously ignores the most obvious possible answer. The most obvious answer to ‘why do intellectuals oppose capitalism?’ is ‘because capitalism is intellectually bankrupt’.
That’s not necessarily to attribute to intellectuals a superior ability to ‘see the truth’ of matters. It might alternatively be a matter of how that ‘truth’ is expressed. Loads of people, after all, are pissed off with how society works, frustrated, angry, insubordinate.