Everything that people believed in the past is not wrong. They were right about a lot of stuff, some of which we consider common sense that isn't worth talking about (car accidents are bad for your health) and others of which are now considered controversial (skeumorphic buttons are a good way to distinguish clickable from nonclickable UI).

I expect that a lot of things that I now believe will be proven wrong. I have no idea which of those things it will be.