The missing component is luck I feel, you and I both have probably put the same smarts and effort in as those who were succesful but just haven't had opportunity, effort and luck all line up at the right time.

I built four SaaS products while working full time as a software dev, I have started companies, tried some side hussles, I am a smart chap but I was never blessed with opportunity and luck at the time I was putting in the effort. Then I burned out, and now I am just happy to be enjoying software for a living again. It would take a really captivating idea for me to start another software side gig, and only if a concrete opportunity arises. For now I am happy working on being prepared to sieze that opportunity by building cash, skills and a network, rather than actively working on one that doesn't yet exist.