highly recommend also watching 'Team Foxcatcher' the Netflix documentary for details and answers

it has way more details that are even weirder and also provide much better answers as to why the murder happened... it shows DuPont's schizophrenia gradually increasing, probably due to increased recreational drug usage...

for example, one day he decided that since "black was the color of death" nothing black was allowed on his estate, which included the African American wrestlers, all who were immediately dismissed.

He also believed David Schultz was hiding inside his mansion walls and playing tricks on him.

Prior to killing David, he pulled a gun on another wrestler who had been training and living on the property... this wrestler warned the official wrestling commission that DuPont was getting crazier. They had a conference meeting and almost disassociated from Foxcatcher, but then David Schultz said "If I thought for a second my family were in danger, I'd be gone" - his statement caused officials to ignore the increasing signs of mental illness and ultimately cost him his life.