This needs to be clarified a bit more"Shitshow for AVZ = DRC bad...

This needs to be clarified a bit more
"Shitshow for AVZ = DRC bad business envionment = no/less investment"

You're right that people will continue trying to get the minerals - corruption or no.
but extracting the minerals is NOT investment
and importantly, it doesn't lead to any further value capture for the DRC, just the minimum required to get the materials out of the ground and send them off somewhere else.

What the DRC wants is to move up the value chain. And that does require actual investment - not just out-competing someone else to buy the rights to a resource. And the investment decisions made for those things are different to the speculative value of extracting a resource out of the ground.

Lots of people keep saying that "oh international community isn't going to run away if AVZ loses out to a little corruption"
That's true, probably not. It may not move the needle all that far on the investment decision scale. But it'll still be moving it in the wrong direction. Reputations are hard-earned but easily lost. If you have a bad reputation then yeah some dodgy shit may not make it that much worse, but if you're trying to improve your reputation as DRC is then every step forwards needs to be taken to gradually build that position.