doubt about a friend

I have a friend who I think is envious but I want to know why... I am better than him in many things and when I achieve something big and I feel proud he comes to me and tells me "I was lucky" or says that I will never be lucky twice in my life... or for example I have a high IQ certified by a psychologist and he says it was luck or that I cheated... but when he does something great or excels at something he always gets proud and I tell him: you are a genius you did well... or positive things... but what happens is that he doesn't let me excel he wants me to stay stuck at his level and if I do surpass him he tries to lower me to his level so as not to feel bad... I get a little angry every time he does that to me... but I'm afraid that he will get angry and leave... but it is difficult not to surpass him, I surpass him in many things but he always wants to lower me to his level to feel good... I want to understand why this person is like this... did his parents abuse him and call him a fool?