If they call everything that one don't get paid for "useless" then they are using the wrong word. In fact, the examples that the author cites were manifestly n

If they call everything that one don't get paid for "useless" then they are using the wrong word. In fact, the examples that the author cites were manifestly not useless at all even on the criterion that money is the ultimate measure of utility. In the one case, the work produced a book which, one presumes, some people bought, and in the other case, art (music) that people at the very least went out of their way to listen to, and possibly even paid for. (I've never been to a punk rock concert, but I presume that at least some of them had cover charges.)