Also, a lot of computer-bound geeks with gaming tendencies have a little conundrum when we only have one machine. I'm doing the popular solution of 1 base OS + 1 virtual machine OS, because this is a lot less hassle than dual-booting like solutions. There's no real competition then between gaming on a Windows VM versus doing work on a Linux VM. Not so easy to find occupations that require peak performance out of your machine. At home. When you have hundreds of CPUs backing you up at work.
NVIDIA, Steam, etc. are honestly pretty good with Linux, but it is true that a stable customer base isn't there. Indie bundle stats in my experience always show Linux players paying more per person, but a smaller total fraction than Mac & Windows. Given that several well-maintained distros also work on a philanthropic company or organisation backed model, I don't ever see linux fractions becoming a major replacement (on current projections). There is currently no noblesse oblige in free-market economies, to mitigate the comparative guarantee that company tech support provides for the masses on paid-OSes, as compared to free-OSes.