Younger programmers tend to want to make things, in particular, big things that sound or are complicated. It is a valuable experience to bootstrap your own OS (I've done it). Doing so would impress an employer hiring for an embedded position, but there seems to be a fundamental to how the markets work and the implications for software as a business that a lot of people miss. This is in addition to the usual issues that younger programmers run into, such as being too ADD about their side projects and never really making anything that could be called a "deliverable".
I've met people who worked in systems software who would like to be able to sell their own kernel for a living. While the commoditization of modern operating systems and kernels was known to them, they didn't understand that it meant you had to either contract out for maintenance of forks or sell patched ready-to-go kernels like some vendors. No real room for any genuine creativity in that or for scratching your own itch if you want to make a living off it.
On the other hand, if you take a step back and think about what kind of software projects and domains are towards the top of the "division of labor pyramid" for programming, it tends to be end-user oriented products, usually stuff built on either the web or the desktop. More commonly these days, this is web applications. There's an inversion of the power structure underlying the pyramid these days occurring in the form of tightly managed walled gardens and "web platforms" like Facebook.
It's turning programmers into sharecroppers for peanuts. If anyone ever drooled for cheap labor before, they've been presented the golden ticket for acquiring it. Make the programmers think they can make their own way and set their own rules, but be the gatekeeper to the platform. The raw abuse Facebook API devs have suffered of late is obscene and merits a class-action lawsuit just in terms of the time wasted to fix all existing apps.
This bears a more than passing resemblance to the Amway-type pyramid schemes where people were presented the forbidden fruit of self-ownership and instead sold a system where no one can actually earn a living without being one of the people on top, which is an earnings ratio paralleled in the Apple App store and the indie game market as well. I should mention that Minecraft was a fluke that started with years of previous attempts and a cult of personality that sprouted around Notch, in addition to the kitschy nature of the game.
Anyone who thinks they can "make a Minecraft clone" and make the kind of money Notch made is insane beyond my faculties to describe. Notch had a lot of experience as an indie dev, dumped thousands of hours into games that never went anywhere, and never really considered Minecraft to be a commercial endeavor. I hate to make use a Gladwellian notion, but I think anybody aspiring to Notch-esque success has 10,000 hours to go. That's not to say that indie game developers fall within the sharecropper definition, but rather quite the opposite. The indie game market lacks the discoverability of something like a facebook app, and they frequently lack any legitimate quality or 'product'. More often than not, they barely qualify as a demo and seem to be throwaways. A definition that could be fairly applied to Notch's previous games.
My real concern is that a lot of developers miss the sweet spot in the labor pyramid and either become sharecroppers (too little control) or they make an operating system they somehow think they can profit from (too much control, no product). The sweet spot at present is probably in establishing a business wrapped around a product and service entwined in each other. Alternatively, maxing out your earnings as a contractor and making the flip to sub-contracting your work to expand your billable hours. This an acquisitive way of thinking about it, and not everyone cares about money, unlike the inevitable and avaricious Notch clones that will come. Some people are happy hacking on their OS kernel because they just want to play around.
"I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu)"
Come to think of it, I'm pretty sure that's how Linux started out too.