You didn’t bother to read the linked article, did you? Graeber addresses these points as follows:
Graeber notes that these “bullshit” jobs are more likely to be higher-paid than productive ones: “In our society, there seems a general rule that, the more obviously one’s work benefits other people, the less one is likely to be paid for it.” If “technology frees up resources to work on other tasks besides non-bullshit jobs like farming or building stuff with your hands”, why aren’t more people doing exactly that? Graeber’s answer is that the economy generally doesn’t reward non-bullshit jobs to the extent that it rewards bullshit jobs–it simply pays better to do meaningless work as a corporate lawyer than to, say, grow food and sell it.