I don't mean this personally against you, but people who tend to talk this way often don't understand the sheer magnitude of what colonialism wrought upon the world. And I understand why; it's downplayed in the history taught in the developed world, and generally only brought up where it resulted in more or less "okay" situations once it had more or less passed, like the founding of America. But that's just the tip of the iceberg. Britain was perhaps the most prolific, but it was far from the only nation doing this shit.
Belgium skull-fucked the Congo for nearly a century, and did pretty much every horrific thing they could think of: mass executions, cut off limbs when the people couldn't pay their taxes, bought "land rights" from the locals for gemstones not even remotely worth enough, murdered probably millions of men, women, and children. IIRC the last time I read about this, by the time they were done almost 2 in 3 Congolese people were dead or crippled beyond the ability to work. Those left had no leadership qualities or training, since leadership was always Belgian and they fucked off home. They didn't know how to do pretty much anything other than grunt labor, and suddenly when Belgium left, had to figure out how to assemble a Government.
The kind of damage that does is incalculable. Not just the economic damage, not just the ecological damage from the mining and farming, not just the emotional toll left on the populace, etc. This sends shockwaves through history that will likely take centuries if not a millennium to fully dissipate. And then of course after Belgium left, giving the country back to it's populace, they started funding various tribes sitting on the natural resources they wanted, to start civil wars that would then last EVEN LONGER STILL, doing EVEN MORE DAMAGE.
And this is what just one nation did to one other nation. Colonialism as a whole was a bunch of nations ripping up a sizable partition of the entire planet's worth of places and people, the effects of which, mainly cultural loss/damage, and the incredible wealth enjoyed by developed nations remain to this day and show no signs of slowing down, save for finally the topic of national reparations being on the table.
Edit: And of course colonialist problems or ones that look a damn lot like colonialism continue to this day, from the ship-breaking beaches where workers are paid pennies a day to scrap ships from the developed world, sold to those firms because it's cheaper that disposing of them in an ecologically friendly way, to the exports of trash electronics to various nations where they demolish their environment to scrape out a meager living. People will look at these things and say "well why can't they just have eco regulation and proper laws, and just say no?" and the answer is that a shit job beats starvation, but the fact that those are their only options is itself a relic of colonialism.