TBH the "Economy of the British Empire" article is poorly sourced, especially for the claim that Britain profited from its colonies - the linked source is a Fortune article (even if it has help from an economic historian from Stanford), with only one paragraph on the British empire, and the relevant sentance seems to be this:

"At the height of the British Empire, about 6% of its total output came from its colonies, more than any other Western power."

I don't really understand what this is supposed to mean, since according to the table in the Wikipedia article, British India's GDP was higher than the UK's. 6% certainly doesn't sound impressive. But even then, GDP =/= profit, and being the worldwide dominant power is not really a status that most colonial powers can hope to achieve.