They killed too many in doing so.
Self determination. All peoples are entitled to it. There would be 5000 countries if they were created along those likes and they’d be constantly evolving. Acquiring natural resources were the motives of colonists. How you going to convince them the resources were not stolen? Fiji can thank the Brits for all the folks from India taking power until a coup by the natives took place. Just who was there first? French Polynesia. Who owns the fish in those million square miles, the French, Polynesians, or the soon-to-be Chicoms? There is an independence movement in the Islands.
How many is the right number? Is any lives lost too many for you?