"Motorola and other backers sank more than $5 billion in the 1990s into the development of Iridium, a satellite communications system to connect wireless telephone users anywhere on earth. Although the number of subscribers signing up for the service has fallen significantly below projections and operating costs vastly exceed revenues, this is no reason for investors to back out of the venture. Indeed, it would be foolish to quit now, given the large amount of money that has already been invested in Iridium." True, false, or uncertain? Explain.