How do you convince a kill hungry player that support is good?

HI,

I am a pretty long time league player. I hope this thread is in the right section, as I have never really had to post before :)

With my long standing league career, i have taken on an apprentice (one of many failed apprentices) who is really taking off fast. Most people i ask to play, play bots and still do like 0/20/0 but he dives straight into PVP and gets 15 kills within his first few games as tryndamere. The thing is though, i have been slowly showing him and teaching him mechanics of the game and the teamwork of it, and his downfall is the urge to fight everything. Even if there is 5 people he will run out there, resulting in KD's like 10/10 or 10/15 etc. Well he is pretty adamant about his play style and loves going top and recently as he has been leveling up he has been pushed out of top and into the support role many times.

After his first game as support he immediately PM'ed me in rage yelling about how he hated that champ and it was the worst champ in the game and support is the most boring thing ever! I told him that its not all about kills it is about teamwork and he said he only cares about killing. I responded with "so you don't care about winning? Getting XP and IP? Your kills will never matter your losses will stay with you forever." I then proceeded to explain ELO hell to him as vividly as possible, as I have been there myself in the new ELO days and the very old ELO days (which i must say is much worse.) This kind of shook him but he really didn't care. He just wants to run into battle pillaging with no disregard to anyone else's game experience. I took him into a few games where i let him tell me any support champ to play 1v1 against him and i whipped his ass everytime, showed him some videos about the most epic support plays and support carrys. I showed him a few championship clips where the support absolutely changed the game with their ults, etc. I also explained how assists gold gives close to as much gold as kills, and supports like blitz and alistar, sona and morgana, are fun as hell where you wander around the map bringing doom to everyone who enters your vision, but he said he wanted the "satisfaction of the kill."

After his first support game, anytime he gets the role he just incessantly complains and groans, and it got so bad i told him if he didn't stop talking i would stop talking to him and stop teaching him, and really all he did was stand at turret doing nothing or standing around base. I just think he can't grasp the concept of it all.

I'm sorry if this is asking a lot, but some pro-LOL player's insight would help me out, as i too hated support when i first started playing but i never had problems like this, i actually understood teamwork. Maybe some insights on why support is a game changer and what it's capable of and why its fun?

TL;DR How to help someone understand/teach someone the support role?