We often see the issue of jurisdiction come up:
"BitFinex is in Hong Kong so it doesn't matter what the CFTC says" "Chinese miners would laugh at any order from the US to do anything" "This coin was issued from another country, the US can't govern it"
Wrong.
Yes, legally the US has authority limited to US borders.
In reality the arm of the US law is very long indeed.
First off, the many agencies CFTC, FTC, SEC, DOJ etc. will assert authority whenever the US is involved: if the company advertises, has offices or customers in the US.
There are thousands of regulations from hundreds of authorities which could affect non-US companies.
So, violating US law is easy.
Second part: enforcement. Assuming that someone can shrug and ignore US law just because they are not American is ridiculous.
As an easy and first step, the US could issue warrants for them, the person could be arrested if they ever enter US territory, their US assets could be frozen etc. This step alone would destroy most startups and legitimate businesses, no more US investors, no attending US meetings or events etc.
If they were able to simply write off the US and never return, even that would not help them completely. The US can add an entity to a massive blacklist called OFAC, Office of Foreign Assets Control. If you are on this list pretty much no one in the world will open a bank account or deal with you. If a US or EU bank client even wires to someone on this list then THAT account will likely be closed.
Next step up, the US can add people to various global no-fly lists and lists which make obtaining a visa very difficult from many countries. They can ask foreign intelligence services to watch people, they can ask foreign law enforcement to investigate someone (and it usually will be done so at the highest level). The US can extradite people from most countries and quite often other countries will cooperate with the US on the prosecution side beforehand and the person will face other additional charges in that jurisdiction.
Assuming someone gets past that point....if the US wants them bad enough (for issues of terrorism, massive cartel-scale laundering, issues of national security etc.) the US will simply have the other country grab them regardless of the law...if they are not as friendly with that country they will (as they did with Osama in Pakistan) simply enter the country and grab them themselves.
Other than Iran, North Korea and Venezuela, most countries will cooperate with the US. A rare exception is something like Snowden when the other country gains more by keeping them and this only works if it's a huge freinemy country like China or Russia who can throw their weight around... and even then might not always work.
In most cases it takes a lot less than this...but in almost all cases, a call from the US State Department is all it takes to get almost anyone anywhere brought it. For something as small globally as Bitcoin -- at $9 billion it's less than one medium sized defense contract -- most countries would do whatever the US asked. They are not going to risk angering the largest trade partner / largest military allie/ threat for a trivial sized project.
For a serious enough issue like major terrorism ties many countries would cooperate with rendition, torture or outright assassination of whoever the US asks. (They are not going to go so extreme for something like a theft or hack)
Even something as simple as Bitlicence clearly governs any company dealing with people in New York. So if a company in the EU or Asia has one single customer in NY then they are governed by Bitlicence -- if they violate those rules and the NY Banking Superintendent decides to, they could find themselves arrested if they enter US territory or many other drawbacks.
TLDR: In the real world it's prudent to take Uzs law seriously no matter where you are
I upvoted You