This goes well beyond the metric system. In many ways the US is extremely old-fashioned in the eyes of other Westerners, clinging to customs most of us have abandoned many decades ago. Unless there is a clear economic advantage in it, the US is strongly resistant to change for fear of diluting its still relatively young and shallow identity.
On typical form of American deflection is coming up with elaborate explanations why what works for other countries won't work for America. Sometimes these exceptionalist arguments are not entirely untrue (the US is an exceptional nation in many ways), but they become really transparent when they try to argue why other countries are different. (Most of those arguments just show a willful cultural ignorance, especially remarkable when coming from well-educated and well-traveled Americans.)
No, for the US there is no compelling economic reason to go metric. But that's not the reason why it doesn't, that's just the rationalization du jour. Any other country would not be afraid to adopt the simple convenience of joining the rest of world in a single standard.