Stubbornness and American Exceptionalism are the reasons we don't switch. It's the same reason our politics are so screwed up.
I'm sad I already posted something, or I would have modded you as a troll.
Exceptionalism is moronic, I agree, but it has very little to do with why we don't switch to metric. We don't switch because there isn't a real reason to. By real, I mean that effects anyone's life. Scientists have been coping rather well, and that doesn't effect the general public. We're raised using imperial, so they seem commonsensical, metric won't improve anyone's life here. It would be a big hassle just to make some small subset of people happy. Changing would cost a rather large sum of money, and wouldn't really get much benefit. Sure, we'd be more "international", but who cares?
You are in denial. My bikes have metrics parts. One of my cars had (mostly) imperial parts, one of my cars has metric parts. Some medicines are dispensed in metric, some in imperial. Driving and other distances is imperial, but racers and other athletes are frequently dealing with metric. I am no scientist, but I frequently see articles with both imperial and metric measurements in them (how awkward is that writers have to put both in to appeal internationally, both ways?). Some beverages are in metric, some in imperial. Almost every country in the world uses (predominantly) metric, so there is a cost when Americans travel. And, as you should know, there is a cost to the difficulty of the imperial system. You as a fan realize this, but don't put any weight on the cost? How can you question if it "effects(sic) anyone's life" or ask "who cares"?
There is a cost to changing, but there is a cost to not changing that we seem to be paying in perpetuity.