Don't worry, be happy: the folks who want us to subsidize their Nashville Convention Center say if everything works out just right, we may get by with only a 20% taxpayer subsidy, best case scenario, all other things remaining the same.
Like most large (in this case, humongous) taxpayer funded projects where there is a large industry (tourist and hotel) trying to get funds from taxpayers to subsidize them, the "studies" performed to justify the project are always "best case scenario, all other things remaining the same." And, of course, the scenario is never "best" and all "other things" never remain the same.
If everything is so rosy then surely the hotel and tourism industry would be HAPPY to assume all the financial risks just like any other private business making an investment. But that is the basic fallacy for all taxpayer subsidies of private business. If it can only be "profitable" by taking money out of the taxpayer's pockets to pay for it then its not really profitable.