You're rewriting history (both of you are). Colonialism in Africa was certainly detrimental and exploitative, and not just by standards of today. The "peaceful transitions" you speak of, included borders and methods of government that were set up for the benefit of the colonial powers, the ramifications of which continue to this day. And while independence was achieved peacefully in some cases, colonization itself was a violent process.
Not every case was bad. It was extremely successful in New Zealand with hardly anyone killed (relatively speaking), a peace treaty quickly signed and the quality of life brought up to modern standards, ending 1000 years of murderous tribal warfare. The natives didn't have their own country before it was colonized because they were fractured into tribes. So it was absolutely a good thing to save them from themselves.
"Save them from themselves" is quite possibly the most dangerous mentality to have ever existed on the face of the Earth. The Belgians thought they were saving the Congolese from themselves. Totalitarian states thought they were saving the people from themselves. As soon as you take it upon yourself to decide what is good for someone else, you have decided to become a god with the knowledge of a man. I am quite disappointed to see such ideas supported here.
The Belgians knew they were in it for the money - the main reason it went so wrong there is that they really needed the money now, and so were willing to inflict long-term damage for short-term profit.
Yes, it's very easy to get helping other people wrong, but the answer isn't to give up on doing so entirely.
When you're making the decision yes, I agree it's risky and perhaps arrogant, but with the benefit of hindsight it's clear that it was successful in this case. Not in other cases, sure.
http://trace.tennessee.edu/cgi/viewcontent.cgi?article=1182&...
http://exhibitions.nypl.org/africanaage/essay-colonization-o...