Quote from acronym:
Because vast portions of investment, in other countries, in industry, agriculture, manufacturing, have been driven by US companies.
In the heyday of the british empire, britain was the richest country, because their companies, (often granted monopoly rights over the productive goods of other countries/colonies) were more aggressive, more virulent, more ruthless and profit driven than anyone else-and the backing of the crown/navy certainly helped, nobody else could compete fairly, without risking the wrath of the navy, embargoes or sanctions.
The us has done basically the same thing, 100-200 years later, only with what-1000% more natural resources than britain ever had, and an equally exploitive and determined corporate culture.
this post is the closest to reality, also don't forget that america has noncalculated income, governments are large corporations, these corporations income is generated by collecting commissions (taxes) off of everything, sometimes some companies might rip-off or scam other companies and make some profit that way, say if your company ever ripped off another company or client would you ever file it with the quarterly report? well same with all other companies they'd rather report loses than have people accuse them as being evil and want them prosecuted