How does a wise man get to be so wise? Probably because he’s made more than a few self-correcting errors. Mistakes lead to lessons, lessons lead to learning, learning to knowledge, knowledge to wisdom. When we can reasonably weigh the consequence of a given action in a particular situation, we can choose the proper course of action. If we’ve already chosen the wrong course of action in the past, we can eliminate that from the process. We can make a wise choice based on previous bad judgement. You only touch a hot stove once. In short, old and dumb equals lucky. Old and wise? Well that’s a series of failures that didn’t kill you. And from those, you learned. Wisdom is more than the gathering of knowledge, it’s the application of that knowledge that matters.
I’d take cutting lessons from a nine fingered man before I’d take them from a guy that read about using a saw.