I know when I'm working, and I know when I'm not. Yes, it's inflexible, but it's also predictable. I don't need to work at night, or on the weekend, I don't miss important events in my loved ones' lives because I'm away on a work trip.
I would like more flexibility in my ability to take time off (it was a really nice day yesterday and I wanted to go to the forest), but I enjoy the security and stability I get. Running a business, or contracting, or any kind of hustle isn't really how I want to live my life. I've got enough stress and other shit going on in my life, having 40 hours a week where I can switch all that off is actually quite nice.