I just quit a $1M a year job at 45 years old, moved out of the city into the country, am working to bootstrap something from scratch, and am the happiest I've ever been. (That said, I'm one week into my "retirement", so time will tell.)

I did the math and realized that I had "enough"; anything more would just be working to enlarge my kids inheritance. So there was nothing really stopping me except peer pressure. Given that cultural pressure, it was one of the hardest things I've ever done, and all my peers were simultaneously jealous and incredulous.

On the risk, I think you are really over-weighting the downside scenarios. I realized that given my track record and resume, in the worse case scenario I could always "get a job" if things didn't work out. You will never starve.

And if you are bootstrapping something with low capital costs, you will be able to monitor and see in advance if it's working or not. The decision is not binary. You get to adjust as you go!