Livre d'Or

I think everyone should consider not doing a PhD, and definitely consider not doing one straight out of undergrad (go off, do some hopefully relevant work, gain skills and maturity and all that), but from my experience and that of the PhD students I was close to, it doesn't seem like it's a universal experience. You raise lots of things which can go wrong, and I think it's important for potential PhD students to think very hard about it, put time into picking the right lab and the right supervisor, know what the options are if you don't get along with your supervisor or your first plan of research doesn't work out or it takes you 3.5 years and you have no money left. But I did not think about it in that much depth, and while there's a vast amount of luck involved in that I picked a good supervisor (and he picked good examiners), and I went into it with many of the advantages you list, I had a great time for almost all of the PhD, and even the final few months only got mildly stressful because I was pulling some 12-hour days to finish the thesis. Now, I know that mentally I had some advantages - I am super laid back, and I already knew that there were lots of people who were smarter and better than me and it was not likely that I would come out and get a fellowship or a lectureship or a paper in Nature straight away or even at all - but I don't think I am uniquely suited to doing a PhD, and many of the students around me with different mindsets also did OK in the end.

I don't want to take away from your many good points about PhDs, and I think there are a lot of people who go into it without a good understanding of how the system works (ie, quite badly) or the potential problems they will experience along the way, and it's good to get all the knowledge out in the open. But it is possible to go through the system and come out the other end with physical and mental health intact.