For the first 10 years of my serial entrepreneuship career, I founded 9 startups with angel fundings or my own financial resources. Even though 2 startups eventually went IPO, these two successes paid for all the other failures. It was basically a zero sum game.
So I now do not do startups or invest in them unless they are able to bridge the last mile access.
My secret sauce is to bridge the last mile deployment to get your technology to as many end users as soon as possible by the fastest route.
Not until I do this did I reap ROI from my inventions and technology.