Because you didn't make it. I'll grant that western ideas about intellectual property are weird and inconsistent, but I'm taking it as a given that we hold that idea in common. If a writer writes something, that sequence of words in the order they wrote is their "property" and they get to determine who gets to see it.
I am cognizant that in this kind of space a lot of people probably won't hold this view of intellectual property and there are good arguments as to why it shouldn't exist at all. I suppose at this moment I'm not really in the mood to go down this rabbit hole, so forgive me if that is where you want to go.