If you do not fire bad clients, you are a bad agency owner.
It doesn't matter how much they pay.
(Build a reliable sales system and you won't have to worry about replacing them)
Bad clients delay project timelines.
Bad clients request tons of revisions.
Bad clients make your employees dread working.
Bad clients cause founders to burn out.
As the owner -- it's your job to protect your margins, employees, & yourself.
Bad clients destroy them.