18 months later, I still suck, but most importantly, my mentors taught me how to learn on my own, where to look for documentation, what sorts of problems to look for. I'm definitely not a 'hacker' in the way you're talking about, and every time I think I know something, I get slapped back to reality, but the REAL satisfaction is being able to just keep making forward progress. To be able to sit at a terminal and feel like your startup's destiny, YOUR destiny is in your hands is immensely empowering and a far cry from waiting and hoping your developer is on the same page as you.
One piece of advice, which I still struggle with: don't try to bite off too much. There's a compulsion to understand the entire codebase before you commit to that host startup's project. Don't. Figure out heat you want to get done and just try to understand a tiny corner of that codebase in isolation, then fix it. Keep doing that and you'll eventually have covered the whole codebase.
It's a long journey going forwards, but you'll look back and it'll seem like time has blasted by. Having good mentors in your startup will make all the difference.