You make a good point, some individuals wake up one morning and find themselves owning a thriving business, they built it from the ground up and pride themselves on being able to competently perform any and every role (yes, in many cases these people are delusional). However....
Here's another anecdote along similar lines..
I drove taxis for a few years, the guy I worked for had one of the biggest taxi fleets in the city (Melbourne), his personal wealth was around $AU30 million, he also sat on the board of the city's taxi directorate. He was normally at the depot 12 hours a day, 7 days a week, he and his son did all the repairs and servicing of the cabs, his standard attire was a pair of oily green overalls and steel cap boots. New sales reps often wandered in and asked him where "his boss" was.
His work ethic set a great example, he worked harder and longer than anyone else in the company, consequently he knew the industry inside out and top to bottom. The only job he would no longer do was driving. Unfortunately the rest of his personality was that of a complete *arsehole, he used his depth of knowledge and experience in the industry to bully his son, his workers, other board members, the local council, basically everyone on his radar. Any driver with half a brain avoided the old man and dealt with the son for shift changeover, but if you wanted your overheating cab back on the road fast then you went to the old man with the big screwdriver hung on his right thigh like a six-shooter.
*arsehole - He was a smart, honest, hard working guy, if these traits had been weaker I suspect he would have been "top dog" in a prison somewhere. I'm now roughly the same age as he was when I knew him, the "suffer no fools" attitude has its uses but it just doesn't scale to accommodate people who firmly believe everyone else is a fool.