Dear brilliant students: Please consider not doing a PhD.
Boy, all the articles about Ph.D.'s on HN are so negative.  I had a great time getting mine.  I got a Ph.D. in Chemical Engineering from Carnegie Mellon. I guess it must depend a lot on the subject you're studying. We mostly did classes for the first two years. We got an adviser in the second year, and gradually ramped up the research. I finished in 4 years and 3 months.  Pretty much everyone in the program would finish in 4-4.5 years. Everyone worked very closely with their adviser, and didn't have the "drift" I read about a lot, where students seem to feel alone.  It was do 3 papers, write your thesis, and get out. I really enjoyed the chance to do research, and do a really deep dive on a subject.  They funded everyone, enough to live to a "grad student" standard. I'd do it again in a heartbeat.