You keep redefining the terms. Sorry. Doesn't work that way, and you seem to have a bad habit of doing it.
Successful means enough listeners to continue broadcasting. That is the only definition of success that matters. Doesn't matter where the money comes from to continue broadcasting, as long as it is sustainable.
I am most certainly not redefining. The context was Air America's failure - and an attempt to find a success with their mission and model. Viewership is only part of the equation - the other part being a profitable business model.
Air America was a commercial flop. A financial failure. It has ceased to be. It's nearest equivalent, NPR, receives government and charitable donations.
Air America was the an attempt to replicate the commercial success of the for profit talk radio model with 100% leftwing programming. Nobody has been able to do this in the U.S.
You are correct. A stations success is not measured in number of viewers but in the advertising dollars it is able to attract. Of course the more viewers, the more advertising dollars it generally gets.
After the Van Jones "Color of Change" attack on Fox's Glenn Beck program, for instance, Beck quickly shot up to #3 in viewership in all cable programming and the more he was attacked, the more viewers flocked to the show. But C of C was able to threaten and intimidate enough advertisers to shift their advertising dollars to other time slots so probably Beck didn't carry his weight for awhile despite high viewership.
On another message board at that time, I watched the kind hearted liberals gleefully posting each advertiser who pulled out or who were rumored to have pulled out. Those advertisers didn't pull advertising away from Fox; just from Beck. But Fox also knew Beck was pulling lots of new viewers to Fox in general and they just plugged the ads in elsewhere. All that didn't hurt Beck in the least--gave him more time and much more exposure in fact and almost certainly permanently boosted his ratings.
By contrast, Air America was not able to attract enough listeners to be attractive to advertisers so they took their ad dollars elsewhere. A few programs might have been profitable but they were not strong enough to keep folks turned to Air America and a few successful programs won't sustain any network or station. So Air America subsisted via wealthy donors. When the ratings continued to suck, even the donors abandoned them.
Liberal programming with less substance and more attack dog mentality simply becomes suffocatingly boring to Americans on both the left and right. Air America offered ONLY a liberal voice and thus was appealing to far too few people to be viable.
Fox News, by contrast, intentionally offers a conservative voice in a market in which it is the ONLY conservative voice, but it doesn't offer ONLY a conservative voice. It provides a good balance of all points of view on every subject, does that competently and effectively, and therefore attracts a broad spectrum audience.