City A has a soul night getting a couple of hundred in, drawing in people from city B, C and D as well.
Some of the people attending from City B see quite a few people from their area in attendance and decide that they could put on a night in their city and not have to travel quite so far for a night out.
The Soul night at City A loses about a sixth of its regular 'punters' in one fell swoop.
City C is inbetween city A and B, so many of the people from that city decide to alternate between the venues each month as "City A will always be on next month", causing a further loss.
City A's venue is now down to just over 50% of it's regular customer base, the venue is slightly too big and it's difficult to get an atmosphere going...
People from Cities A, B, C and D bemoan the lack of atmosphere and start dropping off slowly but surely.
City A's club decide to stick to there guns, booking decent DJs, trying to ride out the storm.
Finally after a few bad nights City As promoters can't afford the venue at a loss so the venue closes, and instead of one decent sized venue with decent music, you end up with a couple more smaller nights popping up for a couple of months at a time whilst 'wannabe' promotors/DJs get it out of there system.
So who's at fault?
City B's promoters for wanting a slice of the cake?
City A's promoters for not changing their formerly successful format?
City C's customers for splitting their attendance instead of being 'loyal' to one club?
Sounds a bit daft but it happens....