It sounds like you were a bootstrapped solo founder in all of these cases? That’s the riskiest path, there are lots of other ways to navigate a career in startups that are not quite so brutal in odds or in emotional toll. (In the United States at least)

I have had a decently long career in startups (closing in on 30 years) and never once was a founder, in part because I always wanted to make a decent salary. Being an early employee at a decently funded startup has been a great tradeoff for me and my family. Even if all the equity over the years had amounted to nothing, I’d still have had few reasons to regret this path.