I'm not sure this says why you dropped out. Is your primary reason because it wasn't 'fun'? I'm not sure startups are supposed to be 'fun'. They are incredibly hard ventures to solve problems where others have failed.
If you are literally having zero fun doing something for a sustained period of time you should probably stop doing that. Startups are hard work but there should be small victories along the way that should be fun. There should be fun in the experience of creating something. There should be fun in sharing what you've built with people. If you're not getting any of that and the environment is completely toxic something is probably wrong.
