It's a myth trades people earn this kind of money.
I know a few plumbers from the footy club and they make about 1/3 of what you've quoted. Know a few builders too and I'm sure they'd have a good laugh at the suggestion of earning $400k.
Personally I'm not so sure. Have you looked at the cars they drive and the houses they live in? Many are on one household income too
My educated guess is take whatever number a good tradie tells you he makes then double it. Which after tax is a hellva lot more than a pilot makes with alot less of the heartache but alot more hard physical work.