I think you don't understand Africa.
The American Government has pumped hundreds of billions of dollars into Africa (~$8 billion per year in recent years), to say nothing of European ($20 billion per year) and private programs like the Gates'.
Musk may be an "amoral douchebag," but he could devote all of his time and wealth to improving working conditions in the DRC, and it probably wouldn't accomplish anything.
The DRC is the 4th most populous country in Africa, with ~90 million inhabitants. I don't want to get into a discussion about religion and education in the country, or regarding societal problems in Africa in general -- I'd recommend this book if you want a better understanding of the issues spanning Africa, and the very real problems caused by foreign aid programs as many currently exist.
And I would point out that Musk's total net worth is now on the order of $100 billion -- roughly three years of US / EU aid to Africa.
I think you're carelessly using the words "huge difference" in your comment to play up what that kind of money could do. Anyone could probably do "a lot of good" with that kind of money, but changing the economic structure of a country with 90 million people and a GDP of $50 billion, which is set right in the middle of a continent with 1.2 billion people...
You could definitely make some nice Youtube videos about a clean water well or a school you're funding, but you suggested that Musk could eradicate child labor and change the very economic structure of a country of 90 million people.
What do you expect him to do? I don't think he can feasibly change the economic structure of the DRC on the whole, so...what's your proposal? You say he could break the system. How?