Speaking personally, I can't justify buying a 5D4 in any terms other than "I want" because, well, I WANT a 5D4 even tho' I'm perfectly happy with my 5D3 and it's got plenty of life still in it and it's fully capable of doing everything I have wanted to do with it.
Given what you do with your current camera, what would be your reason/justification for buying a 5D4?
Given what you do with your current camera, what would be your reason/justification for buying a 5D4?