Of your points, this is one that I wanted to address because this sort of protectionism is something which really resonates with people who don't think too hard about it. It seems so simple: "Protect American jobs! The only cost is screwing some foreigners! Why haven't we been doing this all along? Our government must be corrupt or stupid or something." It's a topic which demagogues can latch onto, but the only people who protectionism really benefits are the people in control of the industry in question. Even to the peons in that industry the benefit from protectionism is questionable.
Finally, a cogent argument and the start of a discussion.
You say that protectionism seems good on the surface, but ultimately hurts the country.
Firstly, I think you're drawing a black-white distinction between protectionism and globalism, as if there are no middle ground positions or other policies. We could easily be protectionist in one industry and globalist in another, or "slightly" protectionist (through tariffs, for instance), or isolationist (like North Korea) in some circumstances(*).
Secondly, you're repeating an economist meme without citing references or analysis or even rationale, and making your point by making an emotional appeal.
I claim that the economist meme "globalism is better for a country" is false, in the mathematical sense.
I'm familiar with the globalism rationale as set forth by economists, and I agree that the mathematics show that globalism is better, but the analysis is based on a model that makes many assumptions. Even though the mathematics pans out, when the assumptions don't match the model you can't rely on the conclusions.
It's like Nate Silver predicting Hillary would win the election. It was based on sound statistical models with no calculation errors, but the assumptions were faulty.
In the specific case of globalism, the model assumes an economic and citizen equality between the two nations. Specifically, if both nations allow citizens to acquire and keep wealth, the model works as planned. When this is not true, all the wealth flows out of the wealth-building nation and into the poor nation, where it is squandered and lost.
To be even more specific, someone from Poland or Greece could emigrate to the UK and take a high-paying job (lab tech, dentist, programmer, or similar), but a Brit cannot expect to emigrate to Poland or Greece and do the same. Poland and Greece are rife with corruption, which makes it almost impossible to build wealth. For contrast, a Brit and a Norwegian could realistically swap places, in the economic sense.
Someone in China could do the same manufacturing jobs as Americans, but after a lifetime of work would have almost nothing to show: No paid-off house, or car, or retirement funds. Most of the wealth in China goes to the government, which spends it on infrastructure, much of which is unwisely spent.
Furthermore, a Chinese can emigrate to the US and take a job or start a company, but it's impossible for an American to go to China to do this, even if you live there and are married to a local. The difference in model completely reverses the effects of globalism on the US: It puts the US is in decline, while China experiences impressive growth.
And finally, the idea of "good for the country" in the minds of economists is based on the wealth of the corporations. The welfare of the citizenry is an afterthought in these models, as unemployment rate, and that only because of its effect on the corporations.
For these reasons, globalism is a terrible idea even though it's repeated by economists a lot, and even though their mathematics and analysis is correct.
That is my rationale, and the logical underpinnings of why that economic meme is wrong.
If you have a counter argument, I'd like to hear it... but just restating your position or saying "most economists agree" isn't a proper argument, and making an emotional appeal (which you've already done) isn't one either. (Also, insults don't count.)
To really sort this out, someone would have to model whether the unequal flow of wealth (or goods, or labour) from one country to another still makes globalism good for a country, and use "total wealth of citizens" as the metric.
As far as I know, no one has modelled these conditions.
(*) For example, we could be isolationist in military tech, keeping all the good secrets to ourselves.