Aside from the cost issues, the event is short-lived, a few weeks. An event such as the African Cup of Nations will only be remembered for a while, and then it will just be a footnote in history, fading from the memory quicker than an event like a World Cup. The ACN is focused largely within Africa, when all the PR benefits are best focused towards Europe and higher income countries.  The economic effects are not always beneficial and are only temporary; even the massive building projects have failed to solve the problem with unemployment which is at 27%.