"Colonialism" does not exist as such. It's merely a sometimes useful intellectual abstraction, not a real thing. It has no objectives or purpose, because it does not and never actually existed as a real thing. It's merely a summary shorthand for a certain set of ideas.
Trying to impute motives to an unreal analytic abstraction is the reification fallacy.[1]
Trying to impute motives to an unreal analytic abstraction is the reification fallacy.[1]
[1] https://en.wikipedia.org/wiki/Reification_(fallacy)