i think that is because most of the american have their own job, and they often loaded with the things that they have to do each day in which incorporating other foreign things might be so time consuming and I guess this is real for most of the people who heard about Bitcoin but until today they are still not open about embracing it since Bitcoin was too volatile at this moment and they couldn't risk their money with regards tot his which they can use on other thibgs like building up a business.