No, I am saying that if a project is open sourced, and there is sufficient demand from people willing to pay for support, maintenance, etc, someone will come along to meet that demand.

If there isn't then the original commercial company was obviously never viable either.

Since an entity getting payment for maintenance can neither expect to collect a monopoly rent for the code, nor is required to pay one to anyone else, the cost of maintenance becomes the market price.

I think your view is too strongly assuming that everyone in the market is perfectly rational and perfectly replaceable with zero transaction costs..

Especially when you start talking about a single person company, it could be as simple as the founder being sentimentally attached to the company and continuing it despite making less than they could with other opportunities, but that doesn't mean that if the founder gets hit by a bus someone else will also be willing to take a sub-optimal gig. Or a company might currently be barely worth running with $20k a month in revenue, but if there is a period of turmoil and lost customers in the process of open-sourcing/founder getting hit by a bus/whatever that now the customer base would only bring in $10k a month, it's no longer profitable, and the market fails to find someone to run the company.

If the code is open sourced, there doesn't need to be a dedicated company behind supporting it. Assuming a compatible license, any party that wants to use can fork it and pay people to maintain it for their own needs without advertising that they "support" the code.

But just because something is open source doesn't mean it's easily maintainable by anyone. It's one thing to install and run it somewhere, but if it needs fixes or customization it quickly becomes necessary to learn and understand the architecture and organization of the code, the data models and structures, etc. and if it was previously the product of a "one man shop" then you're going to have to pay someone to do that learning.

Some products are viable as opensource projects but not as a commercial venture, and the overhead of a business entity might be enough to get out of viability.

Your comment sounds like you think open-source work would be _more_ expensive than closed-source work, or did I misunderstand? That would seem surprising to me.

I would assume some people (clearly a minority) would be willing to take a small pay cut when working on FLOSS.

E.G. could someone be paid slightly less at GitLab versus the same role at GitHub, if they believe in GitLab's principles

There are people who value open source and there are people who value assets. The point is that there isn't a single market rate for the two offers since they aren't the same thing.