It's all about blustering threats (that will happen) until the other party concede enough that the threats don't happen. Simple negotiating tactic that works.
Just like negotiating at a car dealership, you spend some time going back & forth & then, if you said that you would walk out if you did not get the deal you wanted, then do so.
Come back in 3 days & see if they decide that they can get closer to what you want, Maybe it's close enough & you buy the car.
Or maybe not & you walk out with no further negotiating. Come back in another 3 days, if the offer is the same as before, you can accept or walk away. If you walk away, don't bother coming back because you won't get the deal that you are looking for there.
Unless you can prove that you have a better deal form someplace else. Then MAYBE they will match it. Or maybe they will tell you to take a hike.
It's the Art of the Deal.