Source is Bill Gates' post-AMA thank you:

Bill Gates AMA 2015:

https://reddit.com/r/IAmA/comments/2tzjp7/hi_reddit_im_bill_gates_and_im_back_for_my_third/

My favorite thing Bill Gates said this time:

There will be more progress in the next 30 years than ever. Even in the next 10 problems like vision and speech understanding and translation will be very good. Mechanical robot tasks like picking fruit or moving a hospital patient will be solved. Once computers/robots get to a level of capability where seeing and moving is easy for them then they will be used very extensively.

One project I am working on with Microsoft is the Personal Agent which will remember everything and help you go back and find things and help you pick what things to pay attention to. The idea that you have to find applications and pick them and they each are trying to tell you what is new is just not the efficient model - the agent will help solve this. It will work across all your devices.

He also talks about how important Vaccines are in developing nations.

Add Bill Gates to the list of people who worry along with Elon Musk and Stephen Hawking:

Despite his longstanding interest in AI, however, Gates also says he is "in the camp that is concerned about super intelligence," which also includes Stephen Hawking and Elon Musk. Hawking believes AI could eventually "outsmart financial markets" and "out-invent human researchers," while Musk similarly believes we could see a "Terminator-like scenario" if we aren't careful about how we manage this technology.

Read more: http://businessinsider.com/bill-gates-if-microsoft-didnt-work-out-2015-1

I love that Bill Gates made some gifs for proof that it's him:

Imgur comments: http://imgur.com/gallery/lBMmhsA

Reddit comments: http://reddit.com/r/gifs/comments/2tzr6f/bill_gates_ama_proof/

From Imgur:

From Imgur comments:

From Imgur comments: