Based on my only social contact working in trades, the income follows a bathtub distribution - a lot of people taking below average, and a sizable minority getting upper middle class incomes, with almost nothing in between. This is the reason why we get the contradictory narratives of great fortunes in trades on one hand, and the statistics telling the opposite on the other hand.

Allegedly, the talent pool is really shallow - with a modicum of intelligence, passion and human skills, it's not that hard to make it. But most of the guys who end up studying trades are the bottom of the barrel who would do badly in any endeavor (or so I was told).