Most of them do really care about sick people, but that doesn’t negate the fact that the job can be physically and emotionally exhausting. Sick patients can be extremely nasty to caretakers.
Many hospitals in the U.S. have adopted a 3 day on, 4 day off or vice versa work schedule for nurses. The nurses I’ve talked to really like this because even though the hours of the days on are long, the long stretch off gives them lots of time to pursue other interests and to recuperate.
My daughter is a nurse who works such a schedule.
She likes the time off to recuperate, plus the fact that the downtime gives her a chance to pursue additional education.