Burnout is something that can happen in almost all walks of life. Even in fantasy football. Setting high standards and then failing to achieve them can make you feel beaten and bedraggled which makes quitting the easiest solution. Clearly you should only take part in a recreational activity for the fun of it.
Doing something and hating it is never a good thing. In fact, it's unhealthy and a symptom to a problem. You should enjoy playing fantasy football. Accept that there will be highs and lows. It's never going to be 100% 'fantasy', despite the name. What if there were ways to deal with 'FPL burnout'? Would that help you?