Is Keurig Etiquette a Thing?

After you brew on the company Keurig is it rude to not throw your used K-Cup away?

Like most people living in the 21st century coffee-driven era via coffee pods, all of my current workplaces have one of these machines. Now I've noticed usually when I open the top to put a new pod in, almost always, there's an old pod in there.

I get it if you're in a rush and it's still hot right after brewing so you leave it, but in perfectly normal conditions, shouldn't you throw the pod away after it's served its purpose? To me, it's kind of like at the gym, when people don't wipe down exercise equipment after they just entrenched the bench or machine with 87,834,135 pounds of sweat. 

Unless in extreme circumstances, I typically will dispose of my pod once it's been used, and I guess I'm a "savage" (I really do hate that word) because I never wait for it to cool down like they recommend. It takes two seconds to throw away.

But I want to know what you think. Going back to my previous example, I really do hate it when someone doesn't wipe down their exercise bench or machine after using it because people can get sick as a result. With coffee pods and K-Cups, unless there's some microscopic bacteria I'm unaware of, you should be in the clear. 

But like almost anything in 2019, everyone has an opinion on it, whether they care or not. Does it bother you if someone leaves it in after use, do you not care at all, or have you perhaps never thought about it?