Arrogance.
It will never win you games !
This is what happens when you get cocky after you are 7.9 k gold in advantage : http://matchhistory.eune.leagueoflegends.com/en/#match-details/EUN1/1133171491/23455941?tab=overview
Basically i've just helplessly watched my teammates start 4v5 fights without me, go 1v3 , jump enemy spawning pool, and towerdive mindlessly.
This is what i got in return for playing my best.