I think you're assuming that most software work is confection.
In reality, or at least in my case, pretty much all the money I've ever earned was in doing bespoke work.
You _could_ see contributions to FLOSS as loss leaders; though that wouldn't be accurate, since there are definitely benefits beyond just advertising your skills.
A key benefit: if there is a set of freelancers working around a single FLOSS code-base, each of them actually benefits by contributing back; because the shared code-base increases in quantity and quality, and thus leads to competitive advantage for all.
How could an architect of great ability ever become wealthy if they weren’t able to just sell the same building design over and over again with no work for decades? Oh wait, that’s the norm.
Earlier you said copyright is unethical and also why should you be paid extra for work you did in the past.
Architects have copyright to their work. They do sell the same plans over and over. No one can just copy their work without paying royalties or at least getting permission.
Wealthy, great architects make their fortunes on bespoke work. Even the plans they sell often have to be changed for each location - it's uncommon that the exact same building can be replicated in different locations over time, due to local planning constraints, preferences of their clients, new regulations, and so on.
Great software developers deserve to make their fortune too and should be free to do so in a manner that suits both them and their (consenting adult) clients without name-calling from developers with different philosophy/orientation.
Copyright is a legal fiction - it doesn't exist except by force of the state, and there's plenty of evidence that it has a large variety of downsides. I think it's entirely reasonable to argue for alternative methods of providing benefit to society that don't rely on having the state threaten people for you.
Or, in other words - the default state of things is that copyright does not exist, not that it does. It's on copyright proponents to prove that we have a better world with it than without.
Great software developers already largely make their fortune doing bespoke work for clients with a need for it. So do great lawyers, great doctors, great system administrators, great technical writers, and so on. This isn't a new idea.
All software isn't line of business bespoke jobs for mega corp. Family business sometimes need software specific to their vertical market but can't afford to employ someone for a year to do it.
In reality, or at least in my case, pretty much all the money I've ever earned was in doing bespoke work.
You _could_ see contributions to FLOSS as loss leaders; though that wouldn't be accurate, since there are definitely benefits beyond just advertising your skills.
A key benefit: if there is a set of freelancers working around a single FLOSS code-base, each of them actually benefits by contributing back; because the shared code-base increases in quantity and quality, and thus leads to competitive advantage for all.