I get why America is upset. From 2001 to 2008, millions of jobs were moved to China and over 40,000 factories were closed. But that was less trade agreements and more tax credits and subsidies given to companies that moved to China. The US Chamber of Commerce, along with GOP Senators and Congressmen, gave seminars in every major city teaching companies how to move to China. You can still find invitations on line.
Regardless of the trade agreements, companies that could move where workers are getting paid $172 a month and don't have to worry about the cost of pollution are going to do it. Especially if they have no scruples.
To me, Donald Trump and Bernie Sanders are two sides of the same coin. Trump is selling Trump bravado. So far, he has made enemies with half the world with his insults. Not a good start. As far as negotiations, you can't compare nuclear negotiations with buying bulk. I think his sketchy tax policies will double the national debt. Not what his followers were hoping for.
And Bernie (everything free) Sanders will never get what he wants from Republicans. And once America finds out the actual cost, probably raising taxes by two or three times to pay for free college and free health care, the middle class isn't going to like all the free stuff. And, the trade agreements. You can't just end them or you will have skyrocketing consumer costs. The middle class will get soaked.
America is angry at our politicians. You had the leadership of one party vowing to do nothing to try to destroy America's first black president. Now, the American people hate all politicians.
Things that need to be fixed, should be fixed. But letting a loose cannon like Trump or a 60's extremist shouting "revolution" run the country is not the answer. Unless people really want to go down the road to disaster.