The vast majority of Linux is not volunteer open source. It's corporate developers. It's also focused on the server. Tech companies seem to use a lot of Macs these days although I assume Windows predominates overall.
Yep. A good chunk of desktop Linux is thanks to paid Red Hat developers contributing to projects like GNOME. Valve pays for a good deal of Linux's graphics-related userspace code. And another chunk of paid work is handled by non-profits like the KDE organization. There aren't as many weekend hackers keeping your Debian workstation and Pop!_OS laptop running as you might expect.
Red Hat almost certainly does less on-the-clock desktop-specific work than they used to though I expect there are still a lot of GNOME contributions from employed developers. I'm not sure there is a good paid contributors accounting survey at this point, but it's still mostly paid especially outside of the desktop world.
