Since you don't offer any evidence for this scenario, I can't really refute it :)

But note that 90% of Africa didn't even get colonized before 1884. That was over a century into the Industrial Revolution era, during which Western Europe had roughly doubled it's population and tripled their GDP.

Looking to the future, I'd prefer colonialism not be considered a lucrative strategy (though the thesis doesn't deny that colonialism was profitable for specific interest groups - just that those groups were a small part of the newly industrializing economies, and that the nation-level balance sheet gained little from their pillaging, compared to the costs of empire-maintenance).