I'm sure you are aware, but theory you are repeating is due to Lenin which he invented as a means to explain why capitalism was working so well and wasn't collapsing like Marx had claimed it would. There has never been even the slightest shred of evidence for it and every bit of historical evidence shows pretty clearly that wealth transfer has always gone the other way - from first world to third world - with a few famous exception such as Belgium.
I've never seen a source that disagrees. Even the sources that talk about how the British drained India of it's resources will eventually admit (in small print somewhere hidden at the back) that "Sure, there was a huge one way flux of capital from Britain to India, and sure it cost Britain a fortune, but in the end they actually robbed India because they implemented a free market system rather than a protectionist socialist system". That is literally the only argument that exists, that by implementing a free trade, free market system, they took advantage of India.
