Earlier quoted context omitted.
Has anyone tried "none of your business" as an answer to why your are leaving?
Seriously. And if that doesn't work, try "I hate you"
Though nowadays, in the era of pervasive financing and Wall Street investors that care more about revenue than cash flow, I wonder if that would even work. Maybe "I'm being investigated by the Feds and all of my financial relationships are considered suspect, and so would prefer to have as few of them as possible"?