There are many different countries and many different actors looting.
Iran, Russia, United Arab Emirates, China, France and the US are country level actors that I know of. I have no doubt there are more. Some of them try to keep the interests of Africa in mind, some are straight up looting (if you make money from a mine but use your profits to improve the area is that looting - this is a complex topic that depends on details)
Many countries are run by a dictator (often their top military general) who run the country for their own gain. Sometimes these dictators are natives who grew up as elite in the country, but none care about the people. Even where the country is a democracy, often the leaders are using corruption to ensure they win elections and then they run the country for their own gain not the people.
Note that I didn't put companies in the list. While there are companies involved, they are all hiding between a country in some way and if you reform the country they are powerless.
The DRC is living a quasi-civil war for the last 25 years or so, following Rwanda's genocide. It did calm down in the 2000s, almost managed to stop but then smartphone happened, and they have open air mines of the stuff we use for touchscreens, and the mineral is used to pay for weapons and salaries. Jihadists tactics in the Sahel are inspired from the DRC civil war one (rape and genital mutilation as terror weapons, random executions).
Wasn't Zuma involved in a ton of scandals and bribery (allegations(?))
Last I read up on South Africa, the ANC's extremely dominant position means there's pseudo-one-party rule, with all the usual downsides that entails. Politicians are not beholden to the electorate as much as to the party itself, because the party controls who's up for what election.
The US/UK political parties are also pretty nauseating sometimes, but they and the free(r) press are hyper-aggressive at keeping everyone honest (to the point they make mountains out of mole-hills/grains of sand)
