Yes, this is the real problem.
Side projects for fun and learning is fine. Nothing wrong with exploring new ideas as long as you're having fun.
But somehow side projects have become synonymous with compensating for misaligned careers. I see too many people working all day (or avoiding work all day) then coming home to work all evening and weekend. Then they wonder why they're burned out and not getting promotions at work.
Side projects can be a springboard to career advancement if executed carefully, but for every 1 side project success story I probably see 10 other people with side projects that never do anything other than drain their free time and add more mental work to their TODO list every day.
Maybe the principle is different though (not startup can bigco)... I did a bunch of side projects in school and at bigco before concentrating focus, so in a way we both went broad then had success going deep.
Just thinking out loud, I think we agree.
Nope. I actually developed two products for the second of the startups, which was the time period I was working on the side projects. The CEO (my boss) and I are still on good terms, and he knew about the side projects while I was working on them.
Startups usually fail because nobody wants what they're building, i.e. the startup should never have been founded in the first place. Certainly this was the case for this one: we were doing a platform for hedge fund algorithmic trading, but hedge funds are usually very resistant to running their code on someone else's platform, both because of lock-in/competitive reasons and because their code & algorithms are their crown jewels and they're very sensitive about running that on other people's infrastructure.
For most people doing the side-hustle thing (and basically all of them doing it successfully), the calculus is "Put in the minimum amount of effort in my day job, get my R&R in the remaining time at work, and spend my mornings/nights/weekends working on the side hustle" vs. "Remain fully engaged mentally for the 8 hours I'm at work, relax when I come home, don't do the side hustle." That's why many employers hate side hustles.
I can't say which one is a better strategy, because it depends on the circumstances. Certainly the bulk of my lifetime income & assets comes from giving my all to my projects at Google, delivering successfully on them, and getting promoted a couple times. But before then I worked at a couple of startups and there was basically zero opportunity for a raise or promotion, because the company wasn't growing and there was no money to be had. And I got the Google job in part because of side projects (non-monetizable, but they showed I knew my CS and could work with a modern tech stack) done after work.