Please explain this thought process

I really need someone to explain my friends thought process to me. He is sitting at Gold 2 and I am in Gold 5. He has peaked at Gold 2 and I've peaked at Gold 4 but tilted and went back down. So let me give some insight to our play styles. He is a one trick. He mains Kha'zix. He will play him in Top, Mid, Support, and Jungle. The latter being the main position and the others are mostly reserved for normals. He also plays Shen, Taric, and Maokai. All be it to a much lesser degree but he plays them. He is a good Kha'zix at least at our level of play but he isn't consent at all. By that I mean he losses games more because he goes Kha'zix and most people in solo queue don't pick for the team they pick for themselves and he doesn't understand this and doesn't do well because he can't adapt his play style. He also finds the fault in everyone else play and never things he does anything wrong (I know pot calling the kettle black.) He also doesn't like to listen to advice from people he believes to he lesser that himself i.e. me. Which doesn't help him improve as a player because he has knowledge and don't I have knowledge he doesn't. My play style is very... Wide. I play just about every single champ (not in ranked.) I have a good grasp of every champs concept (I refuse to play jhin though....) I to am not consent I have a 50ish percent win rate and I find my self doing well in my games. I do feed from time to time and I do tilt and my mechanics need a lot of work but I am more consistent that my friend in terms of personal play in ranked (I know its a team game.) But, here is what I don't understand he trys to make it a point to one up me and make me think I'm lower than he is. For example, in our group of friends we have 6+ people so we often vs each other as groups. Today we had 3 matchs that were 3v3s and in the first two games we went into my team won. First game I was Illoai and he was Shen I destroyed him. Next game I was Mordekaiser he killed me twice in lane because I was careless but I was ahead in farm and had better map pressure and won the game. The third game he was Maokai and I was Trundle and at this point his team is realizing I'm a better laner and they try to put me up agaisnt a teemo on their team so I have whom ever is going agaisnt Maokai push the lane go back and switch and they kept trying to keep him away until the realized they lost alot of gold and exp (Also flamed me for leaving lane agaisnt a Trist and Teemo.) Now we are all friends to of course we talk trash and BM. But, when I do it for whatever reason its a crime. His thoughts were "When Jer (Diamond friend) BMs its okay because I know he is better. But, I can't stand being BM'd by someone I know I'm better than." He had me sitting there just surprised because he didn't mean it in a joking way. He was being serious and was so shocking because as he said that he kept refering to how I could beat him with different champs but he'd rather better at 2 champs that be just good with all of them. But I just beat half of his line up... And he refered to a normal game when he got invaded at his blue or gromp by the enemy support and how our support (another friend) left to help him and I didn't (Please keep in mind he is one of those players that doesn't check for invades he just goes and stands nexts to the camp. I can't tell you how many times he has given 1st blood because of it... And the enemy support damaged him and ward that side. Now with that in mind a decent jungle wouldn't go back there. But low and behold he comes right and gets harassed.) and here was my reasoning he made the mistake of coming back to this side of the jungle and I was under tower with 2 waves of minions vs a jhin as twitch. I was already behind and couldn't risk leveling and lossing exp and gold. So to this day he says there is no way someone who doesn't know how to leave his lane is better than me but he doesn't understand a lot about jungling either. So forgive any errors I'm doing this on my phone at 6a.m. and I'm tried. I just need someone to explain to me why he feels the need to act like a complete dick to me and always try to be ahead when we are both pretty equal... Please share your thoughts.