"Since no one can be proven wrong, every opinion is equally valid, and sensing this, everyone lets fly with theirs." No, every opinion is not equally valid - there is a range of probabilities into which opinions can be classified. The more improbable the belief, the less valid it is. One doesn't have to prove that a theory is 100% wrong, merely that on the scale of probability it scores poorly against a rival theory.…
As far as everyone is concerned, all opinions pretty much are equally valid, whether they actually are or not doesn't seem to matter.