Across the decades of my career in high-tech, I found that repeating the pattern of "Create something you're personally passionate about, then give it away" has directly led to quite remarkable success - not every time, but a surprising amount. Admittedly, I found this out accidentally, since at first it wasn't exactly by choice. It was just what ended up happening after all my original plans failed miserably :-)
While I agree with OP about not always turning hobby or passion projects into businesses, I also realize some HNers may be closer to where I started, as a broke teenager with no degree, no job and no skills, than where I am today, recently retired and looking back on a fairly notable career as an 'accidental' serial tech entrepreneur. So, if you really need the money and/or hate your day job, why shouldn't you try to monetize any project you can? After all, these days everyone's got a side hustle (and 'passive income' was the success-porn meme before that).
Honestly, if you really need to, then go for the money but if you can afford to not go for every dollar early on in an emerging niche, sometimes playing the longer game can work out better. And not only financially, but in other ways like personal development, valuable relationships, practical experience and industry insight. And even in cases where your investment of time and energy doesn't appear to pay off in any tangible way, not turning it into a side hustle can preserve the sense of joy and personal satisfaction you get from it. And the older I get, the more I appreciate just how rare and fleeting that innate joy can be.
So at the end of the day, even if it doesn't go anywhere, not monetizing a passion project costs you maybe a few hundred dollars? I don't really count all the hours because, let's be real, if you're counting hours (instead of hiding them from yourself) it's not really a passion project. And in terms of effort and energy, I've always found doing stuff that feeds my soul tends to renew more than it consumes. So, full disclosure: N=1... but, over the years, most of the things I was unhealthily obsessed about to the extent I poured myself into them with wild abandon - ended up working out extremely well, despite usually having little apparent financial upside at the start. And, being obsessed, I rarely ever paused long enough to worry how much money I would make. To be fair, the 'big win' didn't always come right away but... too often to just be random, it would happen within a couple years - and more than once in life-changing amounts.
To be clear, I don't think there's anything metaphysical or 'woo' about this pattern. It just seems to activate disparate things which each nudge my cumulative odds toward positive outcomes. One unexpected factor was how people responded so strongly to what I was doing because they saw my 'non-mercenary' passion. So much so, that nowadays I tell young entrepreneurs "If you create enough value for people around a real and interesting problem, you won't be able to stop them throwing money at you" by which I mean, over-achieve on creating uniquely transformative value first and if you do that well enough, collecting the money gets a lot easier.
There's also an interesting filter effect around emerging passion niches which are outside the mainstream. In the early days of a new thing, most people don't 'get it' but when you impulsively leap into it because YOU can't stop thinking about it every waking moment (and not because TechCrunch said VCs are funding it), then if you have a sharp eye and good instincts, that can put you near ground zero of the next 'next big thing' before the funding cycle starts.
Sometimes the most valuable part of being on the ground floor in the early days is it attracts others who are smart and have good instincts about cool new things. And in the early days, new communities are still small enough that high-quality individual contributions get noticed by everyone - especially when passionately inspired and freely given. Just look at the careers of the random teens who squandered any hope of dating or sports in high school to waste thousands hours on the demo scene in the 90s. While I wasn't part of the demo scene, I was attracted to a couple similar ground zero tech niches in the 90s and it's spooky how many people I met back 'in the day' because we were all doing 'the best' stuff out of the few hundred people on Earth doing this stuff at all, were people who've gone on to become founders of well-known startups, senior fellows at Google or to invent some fundamental part of what's in my pocket right now. And none of the "cool things" my teenage daughter is impressed I was involved in creating before she was born are things I pursued with a monetization plan or after careful analysis of the TAM (to be honest, I'd already done two startup exits and was a week from my first IPO when I had to ask one of my investment bankers what "TAM" stood for).
The obvious counter-argument is "Cool story, boomer... sadly, the days when a tech nerd could succeed by running toward whatever new thing seemed cool and then naively giving away their time and talent are long gone." And maybe that's true. But today doesn't really feel different. Back then a lot of nice, more experienced people warned me I was wasting my time and talent or that I was being taken advantage of. They were wisely monetizing their time and talent toward a carefully laid plan while I was off experimenting with stuff that didn't even work yet, making toys no one would pay for and spending long nights helping people who couldn't pay me just because I thought the thing we were making was super-cool. While the wise and prudent people with a plan got paid for every single hour - somehow I ended up with generational wealth and most of them didn't. Yeah, maybe it's survivorship bias and in an alternate universe, some other version of me did just waste his time, get taken advantage of and end up nowhere. But here's the thing. Even if I ended up scraping a workaday living together for my whole career and retired after a series of "almost made it" products with nothing but a half-funded 401k, - I still wouldn't trade it. The amazing people and experiences I had and all the joy from creating new things that so inspired me I literally couldn't sleep at night was still worth doing even without the big payday at the end. And maybe that's the difference between fake passion and the real thing.
So I guess, my story is only for the crazy fools and dreamers that old Apple ad was talking to. If what I wrote kind of resonates with you but you also worry about being a chump and taken advantage of - know that there's a version of this story where following your passions and giving stuff away, at least for a little while in the early days of a new thing, ends up working out stupidly well - as long as you're smart, do great work and, of course, actually take care of the business end when the ground floor turns into a skyscraper. Now you just need to decide if you're living in the universe you were made for.