Most white-collar careers consist of a running gun battle of office politics and business relevance to make it to your desired retirement age without getting fired/layed off at an age (much after 45) where you'll never get another equivalent job. The battle doesn't stop for nights/weekends/holidays.

Dentist is like pilot... lot of work up front, but once you get established you just show up, do your thing and make a lot of money, with some schedule flexibility if you own the practice.