--- ascribed to risk expert Dr. David T. Hulett on https://www.gristprojectmanagement.us/statistics/there-are-no-facts-about-the-future.html and http://www.johngoodpasture.com/2014/10/there-are-no-facts-about-future.html. I learned it from Ed Thomas, former head of the FCC's Office of Engineering and Technology. It's cited by various people, see e.g. the search results at DuckDuckGo.
And of course, there's always Yogi Berra: “It's tough to make predictions, especially about the future.”