It can be done. Look at idealscape, jim lewis, etw, marty grunder. I think it takes multiple levels of competency to see the big picture and years and years of learning. It is a constant learning curve and constant evolving to stay ahead of the competition. They say 10 years to build a business, 10 years of improving systems and efficiencies, and then you reap the rewards on the next 10 years.
I think a prime example of success is jim lewis. Look at his posts, he is constantly trying to improve his services and efficiencies year in and year out. Each year finding new ways to be more profitable and making sure he shifting advertising to the newer mediums. And guess what, he has multi-million dollar company and drives an older truck! People like that are watching their margins, and really making the money. It is possible to net 250k+ in this business.... It aint a cakewalk though.