Those words are “I don’t care.” They’re more powerful than “no.”
Because they are such a powerful conversation stopper, I don’t deploy them much, at least not professionally. But sometimes the stars and planets align to a point such that it is appropriate for me to use this phrase. I admit with a hint of personal shame that when this happens and I seize the opportunity to tell someone that “I don’t care” about whatever it is that is bothering them so very very much, it gives me something of a thrill.
I realize that it’s entirely possible that despite my sharing this fleeting moment of elation at the opportunity to engage in low-level sadism, you might not really care that much yourself.