How could you guarantee that the elite wouldn't finance implanted backdoors into the AI? We'd actually need the AI to easily pass the Turing test and even then we couldn't guarantee what it would do.
Corruption is even legal in America.
Watch:
https://www.youtube.com/watch?v=5tu32CCA_IgWe can't hope that AI will magically solve all the problems of today. Humans are fundamentally flawed and this is why we are where we are. There is enough money in the world to find solutions to poverty, cancer and such. The problem is that if someone develops a $20 bottle of pills that cures cancer forever, then the pharmaceutical companies will lose billions of dollars. Hopefully you will understand what I'm getting at. The majority of people (and mostly the elite) are driven by greed.
There is a decent thread (if you exclude the useless posts made by signature campaign spammers) on the downsides of AI:
https://bitcointalk.org/index.php?topic=318001.0Society will have to evolve into a model that doesn't require one to work in order to survive.