One likely reason for an audience deficit is the well-known fact that attendance and abstention are both contagious.

Sometimes an event, a venue, or an entire genre of entertainment suddenly acquires a reputation for being on the up. The people who attend because they actually like what's on offer will then be augmented by many others who show up simply because they believe lots of people like themselves are going to be there too.

Conversely, when attendances start falling, people who never really cared much about the entertainment itself will quickly drift away,seeking the elusive buzz which comes from being a member of the right sort of crowd. Sadly, there's not a lot that the poor artist or event organiser can do to manage this rollercoaster.

If making money is your bottom line, then you have to move on with the crowd. But if your primary loyalty is to one particular kind of activity, then you should keep on doing it for its own sake. If you do it well enough for long enough,then the audiences may eventually return. And meanwhile, remember that a little more publicity may be helpful:

"He who whispers down a well about the goods he has to sell
Will not make as many dollars as he who climbs a tree and hollers."

Wassail!