It’s only one of if not the best selling game every year.

Totally niche appeal, yeah right.

Millions of people.

There are many more millions of gamers that don't even care CoD exists, it fits a small percentage on the world of gaming.

CoD has less players than Team Fortress 2 currently, according to Valve's charts: https://store.steampowered.com/charts/mostplayed . And TF2 has ancient graphics.

Steam isn’t a good metric because they sell the game on Battle.Net.

CoD is also huge on Playstation.

But if it didn't exist, those people would likely be playing something else.

If no pc hardware exists eventually there will be no games to play. Then you will have a bunch of angry gamers at the park pissing everyone off.

If my hobby is ruined and I can’t have fun, I’m going to be an asshole and make everyone else unhappy.

Ahaha are you trolling for entitled gamers? Yeah wouldn't want the real world having to face those. No worries: as long as there are people willing to drop money into expensive gear, somebody will sell it.