Well that's not what FOSS software means, but even if you creatively change what it means to fit, that's still not true. I'm also paid to work on free software. I work on what I like and choose to at my job. That is why I chose to take a job where I am. If I didn't have a job I'd be doing this anyway as I was when I started getting into it as an unpaid hobby for several years. If my employer decided they wanted me to work on something I don't want to, I would choose to quit and look for something else.

That's not true. You are paid to do it, but it can very much be grabbed by anyone for free (as in free beer).