My opinion, too. Just think of the imperial countries of the past (Portugal and its Brazil colony), and what happened to them after they lost the extra income...
http://en.wikipedia.org/wiki/Colonial_Brazil
Of course, colonialism morphs with technology, and what the British empire used to do with ships and cannons, nowadays can be done with its influence in the global financial system.
Or in the case with the US, patents, intellectual property, etc etc
FC