Since when is any sort of trade agreement perfect?
The only reason we are in the situation with China that we are now is that several decades of political support sent vast quantities of manufacturing, tech and other jobs to China. Basically we built up China failing economy on the backs of workers and in many cases entire industries in the USA. So yeah politics but rather disgusting politics.
Actually China has literally turned evil in the last 2-3 years. The only real end game here is a major war that likely nukes millions of people. The problem is we empowered China through our political system to build up its country into a war machine. Frankly it sounds like some of the stupidity that occurred prior to WW2. I'm actually glad that Trump is trying something different because the alternative is pretty disgusting.
An idiot? That is a little extreme considering what we had to put up with when Obama was in office. Just look at what happened to alternative power while Obama was in office. In about 8 years we lost almost all solar electric panel manufacturing, 123 went under and a lot of allied businesses failed. All of this while the administration was supposedly trying to put us on a new direction with respect to energy.
No one said or implied that any sort of trade agreement is "perfect." But starting with a bunch of provisions that a lot of experts find problematic isn't a good place to begin.
What sent jobs to China isn't "political support." It's the globalization of the economy. That's a force you can't fight. Well, you can, but it's a losing battle. This is Economics 101 material.
I think you've been on the right-wing gravy train too long. China hasn't changed anything in the "last 2-3 years," although it's really funny you'd even say that. How long has Trump been elected now? Yeeeeeah.

Talk about cutting your legs out from under you.
I stand by "idiot." Whether you like Obama or Trump, and whether you are a Democrat or a Republican, are irrelevant. Mr. Obama graduated magna cum laude from Harvard Law School. Mr. Trump, despite his claims of having been at the top of his class, appeared in neither the commencement program's listing of students graduating with honors nor the student newspaper's publication of students on the Dean's List. So yeah, add "serial liar" to "idiot." No one should be surprised though, given that this is the buffoon whose solution to forest fires is raking...and who rejects reports he doesn't like as false because he "doesn't believe" them. Yeah, that's a sign of a strong analytical mind right there.
As for the "what happened," we could go on and on all day comparing good events to bad events. I could talk about the incredible economic recovery under the Obama administration and the huge increase in retirement portfolio assets, rather than fixating on one industry. At the end of the day, these discussions, too, are irrelevant. Causation and correlation are not the same thing, and proving causation in a complex environment—i.e., the one where we live—is rather tricky given the number of confounding factors.