@RedDeerGuy1, that too is a different assertion. Knowledge and education have some common ground but are by no means identical. Downright ignorance can be found across the educational spectrum, and so can certainty.
@Kropotkin The Dunning-Kruger Effect says that the less you know, the more certain you are. It doesn’t necessarily follow that the opposite is also true.
A common saying cannot be applied to all things as it’s not even backed up by scientific evidence. If I’ve learned and practiced a lot about baking an apple pie then I’m certainly more than certain that I’ll be successful to bake an apple pie.