This doesn't factor in the number of people who have illegally copied it but would have paid something for it had an illegal free copy not been available. It i

This doesn't factor in the number of people who have illegally copied it but would have paid something for it had an illegal free copy not been available. It isn't equal to total illegal downloads, but it isn't equal to zero either. It's probably also not uniform across different game genres. There isn't really such a thing as "enough" customers either. The more you sell the more budget you have to produce the next game and the more confidence you have that it could be successful.