I don't think it's clear that the DAO represents a 'financial crime'. Especially not on the part of the curators. It is an unregulated, unlicensed investment vehicle, but it's certainly not predatory, and especially not on the part of the curators (who are the only arrestable individuals).

I don't know about the law of other countries, but my home country (Austria) does not extradite its own citizens, no matter what the crime is. However, it is possible that you end up in front of an Austrian court, even if you commited the crime in another country. This will only happen in cases where the crime is actually a crime in Austria. Furthermore, the court will use Austrian law, so US law would be quite irrelevant in that case.

There might be an exception when the extradition request is issued by an EU country, but I'm not sure how this would be handled. Afaik the EU requires member states to extradite citizens and non-citizens to other member states. However, (afaik) the law that prevents Austria from extraditing its own nationals is at the constitution level.

You're missing the point. The DAO does not care about the business climate of any particular country. The curators can reside in any country in the world and finance any company anywhere in the world.

Yes - US law is pretty irrelevant for most people who live outside the US and who don't do business with the US.

How relevant is China's law for an US citizen who doesn't leave the country?

US law is not applicable in some countries, because they maintain independence from the US legal system.