I don't think it has anything to do with lying. The people who say "right now, I'm working on this one project . . . " are usually sincere in saying so. It's just that there are a lot of people who say that, but few of them have the discipline to even get something that works at a minimum level, much less get to a reasonable standard of functionality.

I once read a book on working as a game programmer. This is a highly competitive field, since making games is a dream job for a significant chunk of programmers out there. It interviewed several noteworthy designers in the industry. More than one of them noted that 90% of the people looking for jobs in their shops are of the "I'm working on Foo" veriety. The remaining 10% may not have completed anything more complex than a Pong clone or even a screen saver, but they often get hired.