A bullshit job is one where the worker feels does not contribute anything useful to society, but is obligated to pretend otherwise. About 40% of all jobs in the USA are bullshit by this definition. People feel unhappy in these jobs because they must pretend to work, yet ultimately the work is pointless, so it’s a degradation of humanity. The first half of the book is basically an extension of an essay he wrote in 2013; in the second half he speculates on why there are so many bullshit jobs and what to do about it.
Overall, the book is quite verbose and I skimmed it, don’t think I missed that much. There’s a lot of anecdotes and rambling, kind of like his other book about debt. The author has opinions that lean towards socialist propaganda, for example a naïve belief that people who contribute more should be paid more.