You missed the point of the essay, playing cards or watching tv is compared to spending money on luxuries and doing busywork is compared to investment. The first two probably won't respectively take up ALL your time at the office or bankrupt you because they are both obviously BAD FOR YOU (in excess). The latter two can be perniciously compelling, even though they might respectively bankrupt you or waste all your time, because you're more easily fooled (by yourself or others) into thinking they're worthwhile.