I think that one of the factors which prevent many people from attaining success is quitting on a success.
Seven years ago I was talking to an old friend, and he asked me how long I'd been doing DOMAI. I said it'd been four years. So he asked me: "so what do you plan on doing next?"
"Next?" I said. He then said that most people he knew, when they'd been doing something for three to five years, then moved on to something entirely different.
I forget what I said, but it may have been something on the lines of: "I have a fun business, not too difficult, and it's earning good money. Why would I go do something else?"
I'm sure people have many explanations for why they changed tacks in the middle of something successful. But I suspect that the real reason is not rational, but compulsive. Otherwise it would not be so ubiquitous when it's clear that one of the main factors in achieving success is keeping doing something and get better and better.