I don't know the demographics of Brexit well enough to really pass judgment on the narratives, but as to Trump:

For the bajillionth time, Trump's voters are not economically anxious.  We have mountains of polling data on this at this point.  Trump voters are quite well to do -- They make significantly more money than Clinton or Sanders voters -- and are not generally centered in parts of the country where economic anxiety issues tend to be the driving forces.

His own voters responses on issue polling make this clear.

They are culturally anxious and largely centered in areas of the country where diversity has been rising.

It's racism and xenophobia.  It was always racism and xenophobia.  Anyone who tells you it's not racism and xenophobia is either too lazy to read a the polling or too dishonest to let the polling conflict with their narratives about struggling Rust-Belters sticking it to The Man^TM over trade.

Trump is actually underperforming both Romney and McCain in those areas as well as the South while overperforming the two in the Southwest and Northeast.

Be nice to America. Or we'll bring democracy to your country.