The interviewer coined the word "über-frugal" as a cute way of avoiding a word that the millionaire might have found insulting.
Don't kill the goose that is laying the golden ratings, sorta thing, huh? "Interviewers" and Talk Show Hosts obviously walk a fine line here. The British talk show host, David Frost, was often accused of being unctuous. You can never slather it on too thick for a big ego, of course, but it often gives the audience indigestion. "uber-frugal" (in place of "miserly") is the opposite side of the same counterfeit coin, wouldn't you say, wwh? The judicious use of a foreign word allows a speaker to gloss his defamation off with a veneer of cordiality even reverence, especially if it is accompanied by a smile or other gesture of obsequious regard. Everyone's the happier for it. The defamed ego will never know it has been punctured, some in the audience may be curious enough to investigate the bon mot after the fact in which case they will enjoy a sort of post-prandial chuckle, and the interviewer preserves his reputation as an unctuous hypocrite, all for the betterment of the Neilsen ratings.