I don't really have an answer but I am 40 and I feel the same. I am just senior dev in major tech giant, but work is boring and and unmotivating. I really enjoy programming and learning but I realized 10 years ago that working for someone else is not my thing. Here are few things I have tried but mostly failed at them or got bored:
1. Portrait Photography - lots of fun, you meet great people. Cons are that as an introvert, selling myself and then helping client pose during photoshoot was very draining. Then it was selling time for dollars, maybe one day you can charge $5000 per shoot but most likely you will not create decent wealth for your kids.
2. Real Estate Agent - again lots of fun exploring new places, and meeting great people. But unlikely photoshoots, buying home is very stressful, you will absorb client's stress, and of course so much paperwork and deadlines. I never got started properly. But helped a few friends and it was very stressful experience. Again introvert issues with selling myself to strangers.
Then I have had some ideas and tried/half-assed these:
1. Writing fiction - seems like a great idea but it is really hard to write.
2. Fitness blog/spam - I started with a blog sharing fitness tips and workout and motivational videos. Eventually, there was very little original content, it was just embedded YouTube/Instagram videos. It was generating lunch money with affiliate links and ads, but I felt sleazy, especially, when most of the content on the blog was girls in bikinis or yoga pants. (Men's videos were not that popular). As I got old, I didn't want to do this.
3. Tutoring for devs - Still working on this, started informally where I help my friends with the dev problems they are stuck at work. Working on getting paid clients. It is kind of hard because some people just want you to do their work and I don't want to do that. Then there is issue of security. I don't want to get in any trouble but looking at private code of some company.
4. Related to tutoring, I try to blog about every topic I help someone with. Not getting any traffic. Not sure how to compete with SO.
I am not really sure what my next steps should be, I have tried so many things, people don't really take me seriously anymore. I am really looking for something that I can do online without selling to friends and family. Makes me feel like the bad guy from the Founder.