Every single profession, be they doctors, lawyers, actors, artists, tries to increase the value of their work. Programmers go out of their way to devalue the result of their work (software), with the result that the main ways to make money from software is either to use it to power ads, use it to power commerce (Amazon), or use it to power hardware (Apple) but not really to sell software itself.
> Programmers go out of their way to devalue the result of their work (software)
Here's where I think you're wrong. Programmers, like doctors and lawyers and actors and other professionals, are ultimately being paid for their labor, not the result of it. Result is the desirable thing, but from the professional's point of view, it's just a side effect.
You may think otherwise when looking at e.g. doctors and lawyers, but that's because the results is almost always one-off and thus impossible to copy. When a doctor diagnoses and cures my condition, it's not something I can pirate and reuse the next time, or give to a friend. When a lawyer writes a document for me, I may be able to reuse or share that document, but the actual value is in that lawyer's signature - or provenance in general.
Software is free on the margin. So are musical pieces, movies, TV shows, etc., which is why there's a lot of whining of artists (and/or their publishers) about the Internet killing them, etc. But, again, those artifacts are just side effects for the profession. Money is being made on selling labor.
From that point of view, if you ignore the utopian ideals and the general pay-it-forward morality, FLOSS is still perfectly sensible thing for the profession: software is free on the margin, therefore worthless to sell directly - but it makes sense for you to make more of it, because it's a credible signal of your competence. That is, the way most people make money on FLOSS contributions is by using those contributions to build reputation and relationships, and then leveraging those to increase the amount of money they can charge for their labor.
Or, in other words, at the individual level, the software profession lives by a generalized form of CV-driven development.
There is more to life than merely maximizing one's bargaining leverage.
The equivalent of this for doctors is called residency. It's an early stage in their career, during which they're laboring for free or being severely underpaid, in exchange for (sometimes) some experience, and finally for a stamp that certifies they're the real deal now - which lets them start charging for their labor properly.
Software career progression is less streamlined and less credentialized - there are many paths to necessary skills, and many ways of proving you have them. Open source work is one way to credibly demonstrate the necessary skills, and can substitute for or complement your education or work history in your quest for negotiating a higher salary.
Programmers aren't stupid, we are fortunate that we can make our living using the software we build rather than being forced to sell it.
Open-source software is a gift to the world and humanity. But of course there is going to be the peanut gallery that thinks everything should be profitized.