a novelty that captures the attention of the general public for a relatively brief period, until either people lose interest in it, or the next "big thing" comes along.
also, an infatuation or a temporary but intense emotional attachment toward an individual.
Just as the hoola hoop of the late 1950s, so too did the Rubiks Cube prove to be a passing fancy after it was introduced in the early 1980s.
I suppose Sue's brief relationship with Tim was just a passing fancy for her, as she's since returned to her husband.
Someone who is addicted to obtaining money and building wealth. A money addict and fanatic. Breadheads often work more than one full-time job, and some even participate in illicit activities to "obtain the bread".