Biggest ever sporting mistake

[Jojo15]

Everyone has made a costly mistake at some point. Chasing losses, betting emotionally, or ignoring team news—what lesson did you learn?

[Bosunn]

Not cashing out early 

[mooeily3]

Betting emotionally always burns harder than just not cashing out early, because at least with a missed cashout you still made a logical decision in the moment. I learned that lesson the expensive way when I threw money on an injured star player purely out of loyalty instead of checking the damn lineup first.