Ideas have possibilities, projects have potential, but the work you finish is where you profit.
I think the primary reasons people don’t finish their work is a combination of not knowing where to start and when they’re finished (the first steps they need to take in order to begin a project, and knowing where to draw the line in order to consider a project as completed), giving themselves too much time to finish the project (work expands to fill the time available), and unconsciously decreasing their momentum when the finish line is within sight.
A flawed finish beats pretty procrastination
Even a poorly executed version of your project which may only qualify as a rough draft or a homemade prototype is better than the most pristine of unrealized concepts which still sit on your drawing board.
When you finish projects it means you know how to get things done.
While there are a few notable exceptions, it is far easier to become known for your completed masterpieces than it is to become famous for an unfinished masterpiece.
When you finish projects clients and managers trust you to see assignments through to the end. Everyone starts stuff. Far fewer people finish things.
People who finish projects have greater value in the marketplace.