Once again, the headline does not match the quotes on which it is based:
"It Could Take 50 Years To Reap The Benefits Of Brexit" is not the same as: "We won't know the full economic consequences for a very long time". Nor is it the same as: "The overwhelming opportunity for Brexit is over the next 50 years."

Of course Dave will say he has read the whole article, and only given the headline as a link. But that does give the impression that Rees-Mogg said "It Could Take 50 Years To Reap The Benefits Of Brexit". Many people will read the title of the link, and go no further.