Because Hitler believed in "Aryan racial superiority" and when an African America named Jesse Owens won his first medal in the Olympics Hitler didn't want to acknowledge a non-Aryan athlete’s ability.
So in the end Hitler was embarrassed because a non-Aryan athlete won basically ruining the whole entire concept of "Aryan racial superiority"
Hitler was racist and was angry that an African American won because he wasn't his ideal Aryan blonde blue eyed person winning the Olympics.
