You also have to compare NASA's incredible success rate to others in their field. In 2013, China's Yutu moon rover broke down in less than a month. In 2014, the ESA's Philae lander failed to launch its harpoons and fire the thruster necessary to attach the probe to the comet's surface, and ultimately bounced into a dark crater. In 2011, Russia's ambitious Phobos-Grunt mission to return a sample of Martian soil never got beyond low Earth orbit because of a rocket misfire.
I'm not saying other space agencies aren't doing impressive and amazing work. (Both Yutu and Philae were able to keep functioning and achieve at least some of their mission objectives.) I'm just saying space exploration is Really Hard. And NASA and its partners keep succeeding, even when they try crazy new things, like landing the SUV-sized Curiosity rover with the Rube Goldberg-like "Sky Crane maneuver", or sending a nearly two-decade-old spacecraft through the narrow gap between Saturn's rings and the planet's atmosphere.
We take their successes for granted, like this stuff is easy, but it's not, even for teams of well-funded geniuses. Worth taking a second to appreciate the engineering achievement as well as the science.