Thank you. You raise a very interesting point, and I completely agree that predictions should be given much less importance. But, as you say, it is human nature to trust people who look confident, and therefore predictions do hold weight and a lot of people abuse that.
I disagree about promises though, I believe if you promise to (not) do something and then break that promise, you should be held accountable for it. Otherwise, people will keep promising more and more outlandish things, because you eliminate the downside.