From my thoughts, there are three important factors contributing to the surge of Trump and Sanders.
1) Establishment versus the general people.
If votes were cast according to the media and establishment, Trump should have lost already and Sanders had no chance at all.
The establishment or the media always want to control and manipulate how the general public vote. Sometimes, people will rebel. By trashing voters as uneducated or not highly educated is not helpful.
2) The society is changing.
For example, 30-40 years, being a socialist or communist in the States would sometimes face a hard/jail time. Now ,the younger generation who do not go through the cold war, may still get the bad feeling of socialist from media or textbooks, but the hatred, fear or dislike to socialist is relatively light.
A faked unity will not hold the country together. People in the same party should recognize the diversity of opinions.
Try to ask one group to sacrifice and promote unity will not work. We probably have to admit the country is more divided than ever.
3) Change is good, anyway, for many people. Even we don’t know change to better or worse.
Change means hope. Hope is always good.