The desire for convention centers is simple: it brings in visitors with outside money who consume things that are taxed at higher rates (alcohol, hotel rooms, rental cars, etc). From the city’s perspective, it appears to be a win-win. But, these investments come at a cost. In this case, the cost is increased competition. The number of conventions and total number of people going to conventions has decreased since it peaked in the mid-1990s. The situation we have now is that of more cities are competing for fewer dollars. It's a classic race to the bottom.