Curiously, Bill Gates just talked about his greatest "fear," by which he means the thing he has been working for the last 2 decades.
"Bill Gates: ‘My biggest fears about what's coming next for this world’"
"When I ask which challenges to global health security he fears the most, Gates outlines three: antibiotic resistance, cuts to government funding to improve health in the world’s poorest countries, and the next unknown disease, referred to by the World Health Organisation simply as ‘Disease X’."
https://www.yahoo.com/news/bill-gates-super-successful-held-041636204.html