Divide and conquer is a know strategy for the past 3000 years. This is nothing new. Any competent African foreign policy should know about this.
It's more personally profitable to allow the Chinese, French, Arabs, Other Euros, to plunder the natural resources than it is to share power, share resources, and develop the country. It took the Euros's hundreds of years to build their social institutions. And even then Russia is trying to rebuild it's "historical" sphere of influence and have Eastern Europe as a buffer zone and place to exploit.
The root word of Slave, is Slav, as in Slavic Countries - who were peoples forced into slavery in the middle ages.
Same happens in East Asia, South East, Latin America, and pretty much everywhere.
Even within these parasite/colonizer countries, their business, political, and military elites keep as much wealth to themselves as long as it's generally tenable to the populace. Folks suffer, just not too much as to pick up arms.