I really can't see how working 14 hours a day and over the weekend can make anyone happy.
Apart from the doctors that will be paid very good money to help these poor guys to recover from the extreme burnout obviously..
Just take the amount of time you spend per week on hobbies (whether that's reading hn, watching TV, whatever) and add that the the amount of hours you work at your "normal" job. Then you'll understand how (many) scientists can be pretty happy working 12-14 hours a day.