The du Pont family was (and still is) one of the richest families in the U.S., perhaps even in the world. Their money was made in the first place from making munitions, weapons, the tools of war, and then in addition there was the huge Dupont chemical industry as well. This movie is not really about all of that, though it is a subtext or presupposition to the film. This movie is about John Eleuthere (though he preferred that the E stand for Eagle, rather than ‘freedom’ or ‘liberty’) du Pont and to some degree about his mother.
John is a case study that Freud would have had a field day with. He had a domineering and controlling mother whom he sought to please (played ably by Vanessa Redgrave), and John grew up very much alone, without friends. In fact in one revealing moment in the film he explains to Mark Schultz the wrestler that he learned after the fact that his mother had actually paid his one school chum growing up to be his friend. He was a small man, who sought to overcome this through a fascination with wrestling. Vicarious thrills. He fancied himself a wrestling coach, and set up a training facility on his property at Foxcatcher Farms near Valley Forge, and then offered lots of money for the U.S. Olympic committee to make it the official training facility for the U.S. wrestling team as it prepared for the 1988 Olympics in Seoul.
All the money in the world however couldn’t buy John real friends, and real coaching expertise, much less real wrestling skill. If you can’t be macho then hang out with the macho and get your thrills vicariously. Alas, John’s mother saw wrestling as a crude and low sport, beneath the dignity of the du Ponts, unlike the sport of champions, which she favored, namely equestrian sports. She loved horses. And so no matter what John did, it was never ever going to be good enough. In one pathetic scene John shows his mother a trophy he won at a senior wrestling contest (which he funded and sponsored, and his opponent was paid to let him win), but she would not allow him to place the trophy in the same case with the horse trophies. There were no real friends, not much parental love or encouragement if any, and great wealth has a way of isolating a person, and so making them miserable, and even twisted. And eventually of course, this leads to explosions…. not entirely surprising in a family that became wealthy on the basis of explosions and destroying other peoples lives and homes and the like.