Classic line... the better question is: "Why can't developers see into the future?"
Programming is one of the worst jobs for dealing with people. Managers assume you have no life and work you 12 hours a day for a software product, telling you that it might save your job. It's all a ruse; once they get what they want, why pay for an expensive developer to support your new site or application?
If anyone asks me if they should be a professional developer I tell them 'Run away!'. I don't wish the experience on anyone.