I didn't downvote. Even relatively rich countries outside of Africa like Mexico, Chile, and Panama have very high violent crime rates, but mostly among the poor (in Panama anyway, in Mexico I suspect there's a lot more drug related violence.) So poverty is definitely a big issue, but tribalism plays a big role too, e.g. bloody civil wars and ethnic cleansing. A lot of violence in South Africa is either race related or tribal. So it's not that you're wrong, it's just that the picture is more complex than just poverty alone.
That said, I do believe that poverty is the more significant issue. Increased development generally correlates with stronger government [1], and with better access to government. When this happens, disputes are more likely to be resolved through the legal system.
I'm not an expert on the interaction between tribalism and warfare in developing countries, so don't think I'm trying to claim infallibility. This is just what I believe to be true.
[1] I say correlates, because I can't say that development causes stronger government. It could be the other way around
EDIT: Okay, now it's my turn to ask: what did I say wrong? Would you like to discuss it, rather than just downvoting?.