I sold an integrated estimating/CAD/manufacturing software package into the large commercial MEP vertical about 15 years ago. there's good margin to be made by contractors that had shit together, but that was about 20% at best. When the economy is booming and there's more construction demand than there are contractors to fulfill it, those dudes could convince themselves they had it figured out. But when the tide goes out, like in 08, its pretty easy to tell who had their shit together and who was getting by with all sorts of leaks in their workflow. The good ones had money in the bank and didnt want to lose their best employees, so in the downturn they were buying new tools and training their employees up on BIM which was just getting going at the time. Most of the others laid off about 80% of their staff or went out of business.
My territory was New England (mainly Boston and NYC/NJ) and there were some characters running some of those large commercial contractors. I had just started a demo for a drafting department and the f'n owner of the company sauntered in the back, put his feet up on a table and lit a huge joint. Proceeded to give me shit the entire time, but when he heard their competitors were buying, he stroked a check. That company was one that did not survive 08. To the best of my knowledge, they never even took the shrink wrap off the DVDs they paid $60K for. They sent two guys from Boston (who drove) for a class, but they spent the first two nights getting fucked up on 6th and missed the next mornings, so they just got back in their car on day 3 and and drove back to Boston, lulz. Anyone that would put up with that bullshit aint gonna make it.