Thing is, this takes in account: Professional Rigs, Enthusiast Rigs, and other applications that require a beefy system. Steam has like 70 million members and only 7 million have rigs better than the PS4, or on par. No way in hell that the 21 billion is going to "PC Gaming" and no, it isn't counting, "enthusiast hardware", since that's pretty much 770 level and above for gpus and other expensive parts, the PS4's specs aren't even "enthusiast" class, so that'd be like saying the 7 million people with better rigs than a PS4 spent on average $3,000 on their rigs, which is inaccurate. Using this very logic someone can simply come to the conclusion that PC Gaming hardware is much more expensive than Consoles, especially for enthusiasts, and then hundreds of thousands of "enthusiasts" parts are bought by huge studios and rendering farms, so yeah, in hindsight, not very impressive.