The mistake was for Britain to ally with their traditional enemy, France, in the first place.
And as far as Belgium went, screw them, after what they did in the Congo, the Germans never did anything like that in their African colonies.
That suggests they should have actually allied with Germany. There was enmity there from the time Disraeli had to put Bismarck in his place, and the German “state socialism” of that era was the natural foe of English common law.
So what was done to the people in German South West Africa and German East Africa was simply not as bad as the Belgian Congo due to numbers?