So, I own a Keurig machine. And I'm feeling a bit of discord here - I'm abhorred when I see people blithely tossing water bottles into the trash (Don't they care about polar bears?!!), but I have this Keurig machine.
In 2014, enough K-Cups were sold that if placed end-to-end, they would circle the globe 10.5 times. Almost all of them ended up in landfills. Given that K-Cups eliminate the hassle of a drip coffee maker, people are mostly just tossing out the cup. Theoretically, you COULD recycle them. However, since the K-Cup plastic is integrated with a filter, grounds, and plastic foil top, there is no easy way to separate the components for recycling. People who pay for the convenience of K-Cups are probably not going to go through the trouble.
Maybe you're a climate change denier. Here's a fact that might get even you, the wearer of the tin foil hat, to reconsider your K-Cup: you're paying between $40 - $50 A POUND for coffee grounds! Another thing I find annoying is that Keurig came out with the 2.0 machine specifically as a response to all the knock-off brands that arose after their design patent expired in 2012. You can't use any other cup but K-Cups in the 2.0.
Monsters made of K-Cups! Yikes!
So, what to do? You could just, you know, NOT use K-Cups. But if the thought makes you shudder, there are a few options. The San Francisco Bay Coffee Company has eliminated most of the plastic in their coffee pod (pictured below). What's more, if you buy the bulk box on Amazon, you get a little doohickey that modifies the Keurig 2.0 machine so that other pods are compatible with it. Real Good Coffee Company makes pods that are recyclable, but again, the pod has to be disassembled, and they are not compatible with 2.0 machines.
I think the most earth-friendly option if you plan on keeping your Keurig machine is the reusable coffee pod. There's no landfill waste if you compost the coffee grounds (which of course you already do, right?) By the way, if you do compost,most Starbucks locations will give you their daily used coffee grounds for free.
As for me, I've gone back to the drip coffee maker for the most part. I've got a little green reusable pod, too. I do keep a few traditional pods on hand for "emergencies" (i.e., oh crap I got up sooo late, don't have time). I also started vermicomposting (composting with worms), so my little wormies are very caffeinated!