The real answer is that when countries have superior militaries, there is pressure by wealthy parties to use those militaries to go to war and make the wealthy people even wealthier, via stock ownership in the companies receiving military contracts. This has been true throughout history. Our military is especially strong, so this pressure is surely very great.
Americans do not go to Africa much, so they really have no idea what goes on over there. We only know what we get through the news. These days there is no investigative journalism; all news comes from either "official" sources or the Associated Press. So if we wanted to start wars to "stabilize" Africa in a way that is friendly to our interests, all we would have to do is create an enemy out of nothing and send troops to "rescue" the Africans from them, or find some pre-existing minority rebel group and give them lots of guns to overthrow some government we don't like. There is tyranny all over the world, but what gets reported is what people want you to hear about. So when you hear about the same groups over and over, that came out of nowhere and we are suddenly asked to be concerned about, perhaps this is just someone getting us geared up to send in troops to "maintain order" in a certain part of the world.
To the military the world is a chessboard, and our military hopes to capture all the pieces. There was a guy many years ago who wrote a plan for the USA to take over Russia, and the whole plan begun with (and hinged on) control of Ukraine. Maybe this is the real reason we talk about sending troops to support the neo-Nazi rebels who literally took over the Ukrainian government by force with sniper attacks, who we try to pretend are the real Ukrainian government, and part of why Russia chose to oppose the actions of this new rebel government. Not that it's related to the question, but here's some food for thought: Which country do you think would play the greatest hand in Ukraine's politics, off the top of your head? The USA, or Russia?