The USA have the largest economy of the world, therefore it provides the most opportunities for business. Unfortunately unscrupulous individuals also take advantage of those opportunities.
I think the answer to that one would be something like "For broadly similar reasons to those for which so many other countries occasionally do the same thing (but more often and much more eagerly, in the case of the US)."
Except the US doesn't like to extradite its citizens when other countries want them. At least not for financial crimes. Bringing up again the 2 cases, the Sarao and Kim Dotcom. Sarao's crime (which was itself a crime only in the US) didn't hurt anyone. And they tried to blame the flash crash on him. Not to mention he was arrested a few days before the crime would have expired. If they knew about him, why didn't they arrest him right away? Kim Dotcom is a jackass, but statistic showed that movie piracy doesn't really hurt studios, they are trying to get him for the sake of a couple of Hollywood honchos...
So pekelo are you for strong and effective regulations to keep crooks away or are you for NO regulations ( irrespective of which country)
How about in between? Just because the mighty US can force other countries to help them out, that doesn't mean it always should. Also, if the crime is more or less victimless (Sarao's definitely was) and it isn't even a crime in that country, they shouldn't be extradited. If the criminal is a murderer, sure, go and get him. Speaking of murderer, there was a case where an American murdered a fellow American in Australia. He got jail term there, then when he came back to the US he got arrested again. It sounds to me he was prosecuted twice for the same crime... Just to underline my point, let's look an opposite case: Let's say a Putin critic is wanted in Russia because he criticized the dear leader, what happens to be against the law there. (let's assume) Should the US extradite this person just because he committed a crime in Russia, although that isn't a crime in the US? Although this is clearly a political case, you get my point... Now Sarao's case is different from Kim's because when you become a trader you agree that you will follow certain rules and regulations, one of them outlawing spoofing.
The full cast of characters surrounding Navinder Sarao are the real bottom of the barrel. This one article alone could be made into a mind boggling movie showcasing some of the true scum of the earth. Mind boggling read . https://www.bloomberg.com/news/feat...sh-crash-trader-s-50-million-fortune-vanished