At what point do diminishing returns kick in? Lol

Who's buying it? And why aren't they buying it used? xD

I remember when one guy on this site said that the only reason Mario Kart Wii sold so much was beacuse it was bundled with a wheel...

The people buying this are not, generally speaking, active inthe wider video game Market. They're probably not aware of used game retailers, or the other channels through which to buy used games.  

That's what I call legs.

A true beast, and a platform exclusive to boot, so it doesn't even have the luxury of selling across multiple generations and a nearly 300 million strong install base like a lot of other 30+ million sellers do.

It's probably largely ancillary markets like Latin America, Eastern Europe, Russia, India, etc.. I don't know too many North American retailers that still carry any Wii software, even Wii U has largely been cleared out. I believe MKWii also is preloaded with Wii Mini consoles, so if Nintendo is still shipping a tiny amount of those or have deadstock that they're moving out, that likely could account for a chunk of that.

Crazy to think the game can shift that many units in a quarter. But we did get Just Dance 2019 on Wii. So the platform isn't completely dead. But it's getting there. The Wii Shop is about to go completely dead in 2019, and the hardware has been discontinued for about 5 years now.

Mario Kart Wii is a great game. I think the gameplay is better than Mario Kart 8, although 8 has more tracks and better graphics which is nice.

It shows up in Amazon's top 100 video games list quite frequently. Hard to believe it would still be selling 150-200k a year this many years later, when it's console is dead and online is shut off.