This rings true. I would only add a comment I heard someone say: a PhD is not an investment. It is an expense. If you want to invest in your education do an MBA or get certificates. Those are investments that will pay off later. A PhD is an expense you pay to do whatever research you want to.
On the student lock to the PhD it may also be because students get scholarships. In my case my government gave be a scholarship to do the PhD. And at some point during the degree I pondered whether to continue, but I couldn't have stopped because I then would have to return the money I spent, which of course I didn't have. My supervisors were great. But one can imagine the pressure of having shitty supervisors on top of that.