Most people who don't read history don't realise that most people are repressed by one system or another. The African tribesman for example was oppressed by the African slave trader, the tribal chiefs, constant tribal warfare and by the religious superstitions taught by the shamans. When Europe was colonising the overall benefit brought to the conquered territories was great just the same way as when the Romans conquered Britain it brought huge benefits that dwarfed any tribute extracted. There is such a lot of liberal angst among so many naive people who don't logically follow through their thinking and just blame great powers for the problems of everyone.
No territories were virgin indigenous land that hadn't already been carved up by politics, wars, tribes , treaties and colonisation (Britain itself has been invaded, colonised, united, broken etc. by Danes, Germans, Normans, Romans, Celts etc.) . Is anyone whinging that Europe's issues stem from post Roman Empire? In fact a cursory look at the break up of the Roman Empire shows how society initially regressed in the chaos (Saxon England stopped using money and abandoned many Roman cities). There were terrible things about the Romans but the systems that they replaced and in turn replaced them were arguably much worse (if you think Roman punishment severe check out the Viking Blood Eagle.)
When Europe colonised it didn't find idyllic societies and simply destroy them; it found cultures ruled by kings , divided and exploited (for example the Indian caste system), slavery was rampant ( especially amongst African nations - have a look at who ran those ) , the rule of law was chaotic and brutal (I was reading one commentary from the time that talked about how British colonial troops stopped the tribal practise of tying a criminal to a post , heating a metal rod and forcing them to slide down the post onto it ). If Europe had never colonised the world it is an utter lie to say they would now, and in the intervening years have been free from war, oppression and exploitation and would be first world countries. Most , without invasion and it's cultural lendings, would still be tribal even today (and I include pre Roman Britain in that.) The spread of democracy , technology, philosophy, legal thought , education and trade are what should be focused on not current wars. Countries suffering war now do so because they are socially still tribal or stratified by political religions over which Western colonisation, influence and nation building is a veneer.
A personal lesson my mum told me from my childhood in Rhodesia. She said you could tell the African owned farms from the European because the Africans reverted to tribal farming (grazing goats or low level corn agriculture as their ancestors had done) , the women did most of the farming and in their culture the men went to the town to discuss important matters (drink and play dice normally!) The European farm would be tended, fertilised, productive (remember when Zimbabwe was Africa's breadbasket?) and would employ lots of local people. Mum said that the culture was for the men (or their wives - yes plural) to earn enough money for today and then to stop working and go spend it and that's what many did. Now wind that forward to post colonial now and those farms are all owned by the Africans, but, surprise surprise the ruling party is oppressing its people, the farms aren't productive, Zimbabwe relies on food imports and their leaders blame Britain.
Squalor , poverty and a nations status is in the hands of its own people and it's own local leaders. Colonialism isn't this collosal force of evil as it is painted. Third world countries are third world because despite all the money, knowledge, culture and technology on offer they cling to older traditional beliefs and practices - Ebola is a salient example, spreading largely through an ignorant and superstitious population living a rural existence and suspicious of 'western' technology.