Writing a book is like running a marathon. In theory, anyone can do it if he puts in the work. Completing the task can be incredibly lonely. If you do manage to finish it, you will get the sense of accomplishment knowing that you did something most people don't.
But it's hard. Don't fool yourself. You may have the most inspired idea in the whole history of the universe. But you need to sit and grind it out. Once you've ground it out, you need to go back and edit it. And then edit it some more.
Sometimes, it's easy to lose the way just by thinking about how difficult the task is. The only way a book is going to be written is by putting down the words, one by one. Sometimes, they'll flow. Other times, they'll trickle. They may trickle for weeks at a time. It's those times, it may be easier to not do the work and leave the accomplishment to someone else.