Disclaimer: I never went through a similar situation.

To me it sounds like that you have built the core platform for someone else, as an employee, and you have been rewarded for your work. Problem is: you are an employee and you are tired of that.

My feeling is that what you are really saying is that you would like to do your own thing, but the current situation is too economically stable and good to just give it up. How about keeping consistent with your current role and start working on a pet project? Might sound like an obvious advice but it does really make sense to me given your situation :)