I can't speak from experience, but I imagine a company foreseeing a large demand for a material will gladly pay more for a constant, secure supply rather than pay less for one that could be halted at the drop of a hat.
I once had a conversation with a guy in oil and gas at a party. I'm not sure what his job was but he basically said that in most African countries there is hundreds of millions of dollar of equipment just sitting collecting dust. When a company leaves, the government demands crazy amounts of (bribe) money to export the equipment, to the point where the company just walks away from it and writes it off as a loss.
Much of that equipment, in a place like Canada, is a liability. It must be dealt with properly and that costs money, often far more than the equipment is worth. You cannot just leave stuff in the field. I'd be that many of these companies are happy to abandon oil equipment rather than transport and dispose of it properly.
So this economic resurgence is based on African politics? Not a very solid foundation imho. Canada has plenty of Cobalt. Canada has plenty of everything. It's a big place. But it isn't a poor and corrupt nation where permits may be purchased and safety standards disregarded. Its resources won't ever be the cheap option. One day Congo will get its act together and then Cobalt is back where it started.
FYI, Cobalt is no ghost town. Western Canada is littered with proper ghost towns that shut when their local mine or sawmill closed. Cobalt may be sleepy and poor but nowhere near deserving ghost status.