>>725570019
His dad used to be a pro player until he lost to Endou's grandpa and went on a massive losing streak that sunk his career. His mom and dad also died around the time this happened, so he got perma mindbroken by soccer, getting into the business just to ruin it for people.
It's almost like a soccer version of what happens to Ryo in YGO GX, though not as well executed since it's mostly backstory.