Don't know about those trades, but I can tell you about our longtime auto mechanic. He's scrupulously honest, and he has so much business it's unreal....had to take out his gas pumps to make room, and is making so much money he was able to do away with Saturday hours. He owns several Corvettes and is always looking for more. He and his dad live on either side of the business in little ranch houses. The dad, who started the business and handed it down to him, is worth 7$ million.
I don't think they mind not having degrees.
Auto mechanics must make tons of money. The only problem is in finding one you can trust and who is honest. All these trades require mucho intelligence.