I'll give the answer of why they're so much worse off than anyone in the rest of the continents plain and clear: Europeans had a sense that they were the most superior people in the world that started in ancient Greece and lasted until recently, with some vestiges still remaining in people like you.
Because they felt themselves superior to all the other peoples, and also were really good at warfare, decided to go traipsing around the world murdering and subjugating anyone they desired, meanwhile using their superior weapons against each other in such atrocities as the thirty-years war in Germany, or the French Revolution, or World War I. They especially liked to subjugate Africa as, originally, the local kings and queens and other such people in Africa could get loads of money for trading slaves to the European colonies on the ports.
Once the Europeans decided that they were brave enough, and had enough weapons, they rapidly settled the rest of Africa, declared themselves leaders of the entire continent (except Ethiopia), and then, when the African countries began to want freedom, they just dumped their leadership and left, leaving the countries to sort out becoming democratic and the entire process of nation-hood to themselves. Of course, when there was no real organized revolution and idea for the nation after it was established, this lead to vast unchecked corruption and other terrible acts committed by "presidents" who were known to the rest of the world as harsh dictators. Other nations still have very weak governments, so things that we know and enjoy such as healthcare or transportation infrastructure don't exist and can't be created.
