I have a Ph.D. in mechanical engineering. At the end of undergrad, as Matt Groening stated so eloquently in his Life In Hell comic on grad school, I felt “a deep need to continue the process of avoiding life.” I was in no hurry to join the adult world, so I went for a master’s. Toward the end of that, my advisor asked if I had a plan; I said no, he invited me to stay for a Ph.D., and I accepted.
If you don’t mind continuing to live like a student - cheap housing with no air conditioning, crummy car, particle-board furniture - then that’s one less obstacle for you. Similarly, your office accomodations at work will be equally meager. My office was in the basement of the engineering research building, where a bunch of engine test cells were in operation. My own office was in my own test cell - along with two other grad students. I was OK with it, and so were they, but someone who is status-conscious or anxious to acquire the fineries of life might be unhappy in these kinds of settings.
I was involved in internal combustion engine research, which was a well-funded field, so money was never an issue. The same is not true for all areas of research. Funding issues can cause a lot of anxiety.
My advisor was pretty good. Sometimes a little too hands-off, but c’est la vie. He was very friendly and sociable, and once or twice a year had us students over to his house for a nice party. Most of the advisors in my department were well-liked by the students; I don’t think I ever heard anybody complaining bitterly about their advisor. YMMV.
For the most part, I enjoyed the classwork. OTOH, my research was up and down; some days were good, some days it was like beating my head against a wall. I mostly worked a 40-hour week, not including homework for classes. That changed during the final six months, when I was working more like 80+ hours a week to get data out of my project, boil it down, and write a thesis. I actually enjoyed writing. My roommate was writing his thesis at the same time, and for a few months we established a daily rhythm together, pausing in the evenings to watch The Simpsons and then eat a bowl of Jello on the front porch before going back to writing.
Since graduating, I have been gainfully employed by the federal government at a national lab for the past 10+ years, doing engine research and related things. Most of my colleagues have Ph.D.'s, a few have M.S. degrees. I doubt I would have been considered for employment here without having gotten a graduate degree. As has been noted upthread, money is not a sound reason for going to grad school. Someone with a B.S. and six years of job experience probably would be commanding the same salary I was when I started after grad school with zero real-world job experience. Moreover, they would have been earning significantly more money during those six years than I did in grad school.
Having a Ph.D. does tend to make you pretty specialized. The OP mentioned this blog, which mentions the “two-body problem.” Like me, my wife has a Ph.D. (NOT in mech engineering). I graduated, got my job, and relocated, then met her while she was a grad student. She graduated, we got married, and although we are both still employed, it would be seriously challenging for us to find a place to live that could offer both of us a job in our chosen fields.