You should write because when you know that you’re going to write, it changes the way you live.
[...]
That’s the promise: you will live more curiously if you write. You will become a scientist, if not of the natural world than of whatever world you care about. More of that world will pop alive. You will see more when you look at it.
(аргумент в обратную сторону, почему не надо писать, предоставил (в специализированной версии) О. Генри в рассказе "Исповедь юмориста").