It really isn't. It is to gain support from the marginalized middle class (and of course what you wrote). Dude, we're in a time where nationality, traditions and the existing economy are dissolving. Neither Europe or North America have come up with a pragmatic solution to this. From an economic point of view, Europe is in a ot of trouble and Trump is aware of this.
It's not just traditions either. It's that the younger generation is particularly stuck with unemployment and hand-to-mouth menial jobs with limited skill requirements that places them in direct competition with immigrants.
