An Australian who never been to USA was extradited and subsequently jailed for breaking USA law: https://en.wikipedia.org/wiki/Hew_Griffiths

Afterwards, he was banned from USA.

It scares me that it's becomming applicable where ever they want it to be.

Soon we'll have to arrest everyone for drinking alcohol, because that's against laws in some countries, we'll have to arrest all women for driving, because that's against the law elsewhere, etc. etc.

The list is endless, and, IMO, pointless.

> The american law is not applicable in non US territories.

This is inaccurate in a number of ways. Certain American laws are, on their face, restricted in territorial applicability (others are explicitly not, others are neither explicitly limited nor explicitly unlimited and the application requires reference to principles beyond the individual law in question), and, particularly, certain protections of the Constitution have been held unenforceable against the government in the context of certain actions outside the territory of the United States.

But you can't correctly make a blanket statement that US law is not applicable outside of US territory.

US National laws are restricted to US Nationals, and the territory of the USA. Now, for laws that could apply outside of these boundaries, you are partially right, but these are covered by treaties, agreements, cooperation efforts, decrees and stuff like that between the USA and its friends.

> US National laws are restricted to US Nationals, and the territory of the USA.

No, they aren't (unless you are using "US National laws" as a label you've made up for laws that are restricted to US Nationals and the territory of the US.)

aren't they trying to extradite Kim Dotcom to the US because he broke US law?

Extradition is based on treaties/agreements between countries, and they go both ways to make sure criminals cannot escape just by crossing borders. As for Kim Dotcom, his actions may fall under US jurisdiction as some of its customers and servers were in the USA, and whatever he was potentially infringing (copyright among others?) is protected and recognized by international treaties.

For online businesses it's a lot more risky as your customers and operations may be located anywhere.

It applies to US citizens who are wanted in the US for crimes.

In the US, sure. Not anywhere else in the world.

(I'm not sure where you got the idea that citizenship bears any relevance at all here)

Read 18 USC, then you'll understand the relevance.