"Writing a book can't be that hard, right?"

It's not hard at all. All you have to do is come up with an original story line, characters, back story for said characters, supporting characters, original interactions that occur between characters, and moral of the story.

It's not hard at all. All you have to do is find an editor, and cover designer, and formatter, and beta readers.

It's not hard at all. All you have to do is spend months upon months staying up late writing. Avoid contact with friends and family for weeks at a time so you don't lose the 'magical writing flow' you're convinced you have going, only to go back weeks later and rewrite the whole damn thing.

It's not hard at all. All you have to do is emotional invest yourself into something so personal to you that you feel like you left your bleeding heart on your laptop for the world to see, judge, critique and fucking hate if they want to.

Basically, writing a book is a cake walk. If the cakes are made with blood, tears, and cyanide. So you're right, it's not hard at all.