Why do I mention this? Because whenever I feel like I'm in a difficult situation (not all that much different from yours), I promise myself not to pull a Teddy Roosevelt and do something hasty that I'll regret forever. Neither should you.
FWIW, time is not slipping away. In spite of what you may think here at hn, 30 is not old.
My suggestion: keep your job and stay on your path to a green card, but find a way to do it and your startup at the same time. You have to get creative. Put in a few hours on your startup before work, not after. Get rid of you TV set. Block out huge blocks of time on weekends. Use your PTO for your startup. Work from home a few days a week and squeeze in extra startup work with the time/energy you save. You get the idea.
You're already creative enough to build a startup. Now use that creativity to free up more time and energy to work on it. Forget about the competition and time slipping away; just do the best you can. And don't pull a Teddy Roosevelt.