> the outcomes of post-British colonies are incredible

By what metric? Recall that not all people value the same things.

The outcome of British colonialism in Tasmania was 100% extinction of locals - I mean sure, you can call that incredible as you did, but that was never a word used by Truganini

Jamaica, sure, greatest Winter Olympic team ever .. but hardly the poster child for colonialism and impossible to claim as "better off" than sans or alt colonialism.

Uganda, well, ... enough said.

We can likely agree that the expanding British Empire had a tremendous eye for real estate, resources, and location. The bulk of places colonised by the British had plenty of potential for exploitation and exploited they largely were.

The arc of such colonies once the sun set and the Empire retracted was varied, the lucky ones were able to reclaim local control of their own resources and relations, a good many were largely stripped and left to flounder locked into ongoing situations not of their making.

Most notable examples of both are China and India, where China outperforms India even despite decades of violent Communist rule.