>who is under-writing global maritime security and what do they get in return

The United States. The conventional wisdom is that what the US gets in return is outsized influence in the internal politics of basically every country within that protection sphere, plus the petro-dollar. I don't totally agree with the second part, but that's what you'd find in an "explainer" from Vox or the pages of The Economist.

It's also helped to slow nuclear proliferation.

This, I will grant.

The United States, despite inventing the thing and using it first, has done more to get rid of nukes than anyone.

Everyone. They get the benefits of trade. When piracy happens every nation will participate in ending it as is necessary to protect trade. Why would you think otherwise?

History shows a subset of countries are all to happy to support piracy for various reasons.

It’s essentially a prisoner’s dilemma where individual countries are better off defecting.

Prisoner's dilemma is solved and not a dilemma with repeat rounds (aka trust and relationships). Like the real world. This fits well with the fact that cooperation works, and is why civilization exists.

Yet piracy has been around for thousands of years.

The thing is people and countries don’t all benefit equally from buying into the existing system. It’s the same basic reason people continue to run scams and steal stuff on land etc.

So has trade. Piracy isn't a blockade.

Piracy has been used as a form of blockade.

Because it's not everyone. It's (mostly) the US.

yup without the US trade route protection formalized during Bretton Woods, modern trade could not happen as snoothly as it has and the US is slowly backing out of that position

The tired Zeihan position that has been the same song and dance since his days at stratfor and still as wrong now as it was decades ago. He's also predicted that China would collapse a dozen times now, with timelines attached, and every time that timeline passes and China still stands he just moves the goalposts. He got Ukraine right, but it wasn't exactly a bold prediction and it follows the same Nostradamus method of throwing a bunch of stuff at the wall and hoping some of it sticks.

The US has not been the majority player in policing pirates in a long time and piracy is at an all time low - China and Europe handle the majority of the piracy actions around Africa today, the largest source of modern piracy. Even if the US were to withdraw, and it's just Europe and Asia trading with each other, what navy is going to magic into existence to threaten those trade routes? The 5th fleet is in theory always around to back things up, but even if you look at CTF-151 the USA hasn't had the comm since 2009, and basically all of the anti-piracy actions today are small potatoes and easily handled by coalition members.

Yes, the US navy is the best in the world. Yes, without it, there is less ability to protect these trade routes. But if the people that are doing the remaining trade are the people with the next 20 biggest navies, where in the world is the threat going to come from?

If globalization ends it's not going to be because the US navy took their ball and went home, because you have to go really far down the list of naval might to find people who wouldn't want to still be trading with each other.