Here's Graeber's answer to this argument. [1] His answer is phrased indelicately because the question he was answering was also phrased much more indelicately than yours was:
Well, I keep emphasizing: I’m not here to tell anybody who thinks their job is valuable that they’re deluded. I’m just saying if people secretly believe their job doesn’t need to exist, they’re probably right. The arrogant ones are the ones who think they know better, who believe that there are workers out there so stupid they don’t understand the true meaning of what they do every day, don’t realize it really isn’t necessary, or think that workers who believe they’re in bullshit jobs have such an exaggerated sense of self-importance that they think they should be doing something else and therefore dismiss the importance of their own work as not good enough. I hear a lot of that. Those people are the arrogant ones.
Well, I keep emphasizing: I’m not here to tell anybody who thinks their job is valuable that they’re deluded. I’m just saying if people secretly believe their job doesn’t need to exist, they’re probably right. The arrogant ones are the ones who think they know better, who believe that there are workers out there so stupid they don’t understand the true meaning of what they do every day, don’t realize it really isn’t necessary, or think that workers who believe they’re in bullshit jobs have such an exaggerated sense of self-importance that they think they should be doing something else and therefore dismiss the importance of their own work as not good enough. I hear a lot of that. Those people are the arrogant ones.
http://www.salon.com/2014/06/01/help_us_thomas_piketty_the_1...