Is the client always right?
What if they constantly change their mind? If every other undoes what they asked for last week. If they wait two weeks to reply to your emails and then expect you to have the work done in ten minutes? If they pay late? If they don't pay at all? If they're a bully? Or just a massive dick?
The fact is you chose to work for yourself.
And that means you get to choose the terms of engagement.
You can set the rules.
“You get two revisions”.
“That goes against our previously stated objectives”.
“As stated in the welcome pack, as you did not respond within five working days, I've had to move the deadline back by two weeks”.
“Our payment terms are quite clear”.
“Violation of those terms will result in legal action”.
“I think you would be better off taking your business elsewhere”.
“WE DONT WORK WITH DICKS”
Remember, you're the expert. You get to choose.