Because the people are making choices and don't always select the good ones.
But the world of today could change if those currently in control could be replaced by more humanitarian people.
The world would become alot better if Geniocracy would replace the raw Democracy. And capitalism is a part of the problem too, a big damn part.
Theres supposedly 12 millions of $USD$ per Human being in the world economy. So i guess theres a certain unbalanced and unfairness somewhere that must be solved. And ultra-rich corporatists are not the ones who will solve the global problem of unbalance.