If we use the logic you are trying to put forth then anyone in the world is unreasonable. If you've spent money buying a video game you are just as unreasonable. Because that $60 dollars (standard US retail price) could have been used to feed a homeless or starving person in your country. And every country has problems some are just greater then others.
It isn't unreasonable, immoral, or anything else to spend the money you have on something that isn't charity. If this was stolen money, government funding diverted from charity, or profits from forced labor camps then you'd have a point. But Africans deserve to have quality entertainment and deserve the chance to spend money on such things if they can afford it. It as an event to showcase off regional and local talent.
It was no different then any other grand Hollywood party except for the location it happened. But you don't see people rallying against the spending in Hollywood when thousands of Americans are in poverty and/or starving every year. So why is it only an injustice in Africa?