The colonial system made sense up to a point. Maybe the US was quick to see that and the British weren’t. The British insisted on grabbing every rock they could lay their hands on - and they were strained financially.
Remember I used the qualifier “ultimately”, not “in its heyday”.
Not really -- the British wanted India for its wealth, they got ahold of Australia that was basically unpopulated except for stone-age tribes
in Africa they wanted to connect the north to south and so have a great commercial enterprise
They were strained financially only after the war. Otherwise, the Empire was slowly moving to a Dominion-like status.