I suspect you're thinking of the people who have loads of ideas and make a bunch of false starts, never getting much past the first or second chapter. My brother is one of them.
He started a really great suspense story but stalled at chapter 3 when he ran out of ideas. It's been sitting in a drawer for quite a few years now and he never tried to write anything again. A lot of people love the idea of being a writer. It seems romantic and something easily done because of all the terrific ideas they have swirling around in their heads. Once they begin to write though, they find out it's not as easy as they thought it would be and they quit.
Linnea