In the 72 - 74 timeframe, it seems like everyone and their brother had a CB750 of some type. It was the "in thing" around here. As soon as the Goldwing came out, many 750's were traded in. Others were sold outright as many guys went on to the next fad. The early 70's was a good time for Japanese motorcycle sales. We did not see anything like it again until the past few years with the H-D craze, although I think is has peaked as well.
No factual basis here, just a general observation.