The usual way for calculating those numbers has faulty assumptions. It assumes that price of software pirated equals amount of revenue lost. It also assumes that if piracy were absolutely not possible, the customer would be willing and able to pay full price for the software. Both assumptions rest on shaky foundations.
The most important point is that the money people "save" by not spending it on software or music or movies, gets spent somewhere else in the economy. For the media industry to get a few billion dollars more of revenue, other industries have to get a few billion dollars less of revenue, which in turn leads to a loss of jobs.
The amount of disposable income in a country doesn't magically increase whenever some actors on the market want it to.
