http://blogs.spectator.co.uk/coffeehouse/2014/08/why-britain...
There are only 3 countries in the world (Luxemburg, Switzerland, and Norway) with a higher median household disposable income than the U.S. (using PPP) [1].
Obviously this doesn't tell the whole situation since most of Europe provides more government services, but the U.S. also has a lower tax burden (which isn't fully taken into account in disposable income because of VAT).
Yet the number of folks who want to come to the US is unending, including folks from Western Europe, SK and Japan.
1) All those people are average where they are coming from.
2) All those peopke are coming to America expecting to end up as average Americans.
3) All those people have an accurate understanding of the economic conditions they are coming from and those experienced by the average American.
Otherwise, it's a complete non-sequitur.
There are structural issues with how America works that has prevented trickle-down economics from being a reality.