Had I known that I would go vegan and lose 50 pounds, I would have taken pictures of myself when I was 202 pounds. This would provide proof that it does often result in weight loss.
But had I known years ago that I would go vegan, I would have needed to know the reasons why I did so.
Therefore, I would have been vegan years sooner and therefore could not have turned vegan when I was 27.
The conclusion is that it is logically incoherent to know such an event will happen. Such knowledge prevents that future from taking place. This is why I understand that it could be no other way.