In these troubled times, ostentatiousness is out, austerity in. One person heeding that message is Tom Monaghan, the centimillionaire founder of the Domino's Pizza chain (1990 revenues: nearly $2.7 billion). Monaghan, an architecture aficionado and leading collector of Frank Lloyd Wright artifacts, has decided to abandon his $5 million dream house. Even though it was one-third completed, Monaghan halted construction of the 22,000-sq.-ft. mansion in Ann Arbor, Mich., which he had intended to be the keystone in a development of exceedingly expensive mansions designed by eminent architects. The pizza tycoon, who is shifting his attention toward charitable works, felt he could no longer justify spending so much on a personal whim. Said he: "I began thinking, `My gosh, am I building this out of pride, or what?'" Humility has its limits: he plans to keep his multimillion-dollar auto collection.