The easiest way to "explain" that is to point out that it's bullshit.
Life has never been better. Health has never been better. The poor
have never been as rich as they are today. That doesn't seem to stop
lots of people from complaining about all this prosperity, though.
No matter how much they have, they think they need more and need to
work harder to get it.
It's a fair bet that anyone talking about how bad things are is too
young to remember when most of the American economy was supported
by farmers working 16-hour days in the fields; when children died of
polio and rickets; when an 80-year-old man was a rarity; when fruit
all year round was a luxury only rich travellers could afford; when
smallpox and typhoid and tuberculosis ran unopposed; when even a
typical middle-class family couldn't afford to eat out more than once
a week; when children's toys were board games and wagons instead of
electronics; when birth control wasn't cheap and reliable...
If you're working too hard, it's because you want more than a small
amount of work will provide; perhaps society conspires to call that
level of wealth "poverty", and therefore undesirable, but in absolute
terms it's a pretty good deal today.