For many years there have always been "RADIO HITS" and "PRODUCT HITS." Radio hits were the songs that were all over the radio, but didn't move much product. The singers were usually flat on sales, didn't have big shows, sell merchandise, etc. And those were usually the one hit wonders.
The "product hits" were the ones who didn't chart much, but moved all kinds of product.

The biggest example I would say would be JIMMY BUFFET and MARGARITAVILLE. It never reached beyond number ten on the charts, yet has spawned an empire that is worth beyond TWO BILLION dollars. It wasn't until his duet with "IT'S FIVE OCKLOCK SOMEWHERE" with Allen Jackson that he ever had a number one song. But Jimmy has engineered a career that is beyond the imaginings of almost any artist in history. Hundreds of millions in annual summer rite of passage concerts, resturants, and now a retirement community that will rival the VILLAGES.

So yes, there are a LOT of artists that derive very long and successful careers regardless of radio success. There are others who are ICONIC artists, that build their own genre. Lyle Lovett, kd lang, John Prine, Harry Connick Jr. and many more have succeeded far beyond any radio success. Actually, I'd contend that those are far more successful than just about any of the radio people. So when it comes to having a career, the one hit wonder is the rule rather than the exception.

MAB