It's true. It's all true. And I'll validate it for you.
You have no talent.
You're never going to succeed.
Your agent isn't doing shit for you, and you won't find anyone better.
You can't make a living at this.
You're not a real writer.
Your publisher isn't behind you.
Your work-in-progress stinks.
Your peers don't respect you.
The bad reviews are true.
Everyone is doing better than you are.
You're fooling yourself.
You'll never get another contract.
The whole world knows you suck.
Your last book was better.
No one else struggles.
You need to quit, because you don't have what it takes.
Loser.
You done? Got that out of your system? Good.
Now quit being a whiny little baby and go write.