My purely anectodical experience with this is that when people that own these kinds of businesses say they make $500k a year they mean in their best year they made $500k. What they don't say is that for every year they made $500k they had 4-5 years where they were just barely scraping by. Construction is incredibly cyclical and there are a lot of lean years. I've also found a lot of them aren't great at managing the financial side of the business. A lot of the time they don't actually know how much they're making.