Consoles are dying and PCs are replacing them. Like the original commenter suggested, people want to run PC games. The market has decided that the benefits of compatibility outweigh the added complexity. On the PC you have access to a massive expanding back-catalog of old software, far more competition in the market, mods, and you're able to run whatever software you want alongside games (discord, teamspeak, game streaming, etc.).
Macs are personal computers, whether or not they come from some official IBM Personal Computer compatibility bloodline.
If you consider time zones (not every PC gamer is online at the same time), the fact that it's not the weekend, and other factors, I'd estimate the PC gaming audience is at least 100M.
Unfortunately, there's no possible way to get an exact number. There are multiple gaming PC manufacturers, not to mention how many gaming PCs are going to be built by hand. I'm part of a PC gaming community, and nearly 90% of us have a PC built by either themselves or a friend/family. https://pdxlan.net/lan-stats/
For comparison, the lifetime sales of the first Nintendo Switch would be considered a good year for iPhone sales -- six generations of phones sold >150MM units.
Macs are personal computers, whether or not they come from some official IBM Personal Computer compatibility bloodline.