I would recommend doing your best to try and figure out a way to not leave your job completely, yet still give yourself the time you need to build something wit

I would recommend doing your best to try and figure out a way to not leave your job completely, yet still give yourself the time you need to build something without completely relying on doing it on the side. Can you cut your time back to 4 days a week, and work on your start up on the 5th day? Can you take a sabbatical for a month or two so that you can dive deep on building something without having to completely leave your job? I would assume that if you're that successful that your company would be willing to give you some flexibility as opposed to you just outright leaving, and that you have the financial means to do so. Rather than having this be an all or nothing thing, figure out a way to leverage some flexibility to build while maintaining some connection to your current job/position/company.