While I have no doubt that most Western colonial empires did not have the conquered's best interests at heart, I've read a theory (particularly about the Spaniards and Portugese in Latin America), is just Westerners are in aggregate were just
better at running civilization, which is a horrible crime to utter in some circles, but I feel like the evolution of Western systems of governance, diplomacy, technology, culture made it superior to most civilizations in the marketplace of ideas.
One could see the mass appeal of a faraway king who promises three square meals, a decent lodging, a reasonable legal system, and preaches unconditional brotherly love, to every human being. And even if some of those things are only true some of the time, when taken in aggregate, this led to these people winning just often enough that the scales tipped in their favor over time.
And while most non-Western civilizations were certainly superior over certain time periods in some aspect, those who ended up not being conquered, either had constant contact with the West to know what to expect, or recognized their own shortcomings and rapidly endeavored to remedy them.
I don't think military conquest of a faraway land can be maintained without the consent of the populance, certainly not as a profitable endeavor, and that usually involves offering something to the populance they couldn't get otherwise.
There are plenty of examples of people subjugated for centuries who have kept their religion, customs and identity, likewise most of the jihadists who shout 'Death To America!' probably still like Star Wars.