Your argument specifically looking at African countries is poor at best. There are too many variables for them to retreat to and too many facts you would have to present, too many concepts you would have to explain, and most importantly, too many indoctrinated myths you would have to debunk. It opens the door to too many other myths and flawed arguments. They’ll come right back and ask you “how come WWII got us out of the Great Depression?” Then you’ll have to go into all that, because if you try to stay focused on the issue they’ll think they made a good point and that you’re dodging. Then they’ll say “Well then how come the US did so well after WWII?” And if they know anything about history they’ll say “how come things got so good after the Civil War?” It goes on and on. When you’re talking with people who not only know so little to begin with, but also know so much that isn’t so, you’ll never get anywhere by following their Gish Gallop all over the place.
And this is even more difficult if you’re not intellectually and informationally equipped enough to answer all those questions. It’s just not an effective way to argue, at least not for the purposes you’re talking about. This is the whole point of hypotheticals and analogies. It breaks arguments down to their bare essentials so that people can see the logic of the case…as well as stay focused.
If people will not accept something as basic as a parable about a broken window, there is no way you will have any success with using a specific real world examples they know virutally nothing about. (And which, I would have to assume, you don’t know enough about yourself.)
For more information on how to effectively deal with these situations, see here and here.