> Colonizing only helps the colonizers, not the indigenous population.

I am not sure that this statement is completely true in all cases.

Take for example the Roman conquest of the Mediterranean. Romans tended to win their wars because they had superior organization - they could field more armies, and equip those armies, better than their adversaries, even if their adversaries had better commanders (eg Hannibal).

Once conquered by the Romans, the indigenous population got access to all the benefits of being part of Rome's 'empire' - access to what was then one of the largest trade network, the roads, the aqueducts, the Roman legal system...

I do believe, although, not being a professional historian I have the humility to admit my belief could be wrong, than overall being conquered by the Romans led to an overall increase in living standards for the local population.

Or consider the brutal conquest of what is now Mexico by the Spanish. We rightly remember the conquistadors as being incredibly violent and oppressive, but if large swaths of the local population chose to join them in their assault on the Aztec empire, it may have been because the Aztecs were even more violent - indeed, if my understanding of Aztec culture is correct, the Aztec religion required a human sacrifice every day to ensure that the sun would rise. Compared to that, arguably even the Spanish Inquisition is a step up.

Finally, consider that the practice of slavery in what is now Algeria ended only in 1830, when the French colonized it. Now you can accuse the French colonizers of being vicious brutes (and you'd have a lot of evidence to support that claim), but... at least they weren't enslaving anyone. Of course, this last point makes a value judgement that basically boils down to "slavery is always bad", if you have a value system where "some things, including colonization/colonial/imperialist violence are worse than slavery, then you can safely discount it ^_^