i finished a phd in library and information science two years ago and i'm currently wrapping up a 2-year research fellowship. i'll be starting a tenure-track professor job next fall.
our field is kinda in between the "hard" sciences and "softer" social sciences/humanities. people who want to get technical seem to have no trouble getting jobs in tech/startups etc, i definitely know several who have gone on to google, amazon, facebook, etc. they're all making big bucks. you dont technically need a phd to work at those companies if you have the right skills, but they all also have research teams full of phds. my friends who work in tech without phds often say that it seems like the research team kinda gets to do whatever they want and they have more freedom. i'm sure thats partly just a perception thing but it also makes sense-- phd people are known to be a free-range kinda group. the phd process is a way of proving that you can work independently and contribute mewaningful research with minimal oversight.
i also know people who stayed on the more humanistic side of things, and as many in this thread have said they are struggling thru much a more challenging job market. some are still adjuncting, which really sucks ass and is basically like being the epitome of "overqualified and underpaid." others have secured visiting professor jobs or teaching fellowships, which are not so bad but still unstable. a few have tenure track jobs, mostly at smaller schools but some at big research unis as well. some work in nonprofits, schools, administration, government, etc etc. all examples of "you dont really need a phd to do this" but totally viable ways to make a living.
when i decided to start my phd i was coming off several years of playing in punk bands and doing temp work. i basically decided to go because it was a way to get health insurance, free tuition, and a modest salary thru the job i was offered at the university in my admission package. i didnt like the jobs i was doing before, but i had always done well in school, so i went for it.
over the course of my studies i definitely saw several people drop out of their programs. i took a bit longer than many of my peers as well (7 years, with the average being closer to 5). i actually think that taking more time helped me on the job market because i got more publications under my belt and had more time to make a name for myself networking at academic conferences. the people who dropped out basically couldnt deal with the internal politics of their departments, or the fairly unstrutured environment.
you really need to be self-organized and self-motivated to succeed in a phd because the authority that oversees you is generally very diffuse. the people in charge of your teaching are different than the ones on your thesis committee, who are also different from the people running any lab or grant project you happen to work on. you could stop showing up and nobody would notice for a while. i had already been doing a ton of remote freelance work for years, so i was fine with that. i am also fortunate that for the most part i dont have a problem with people trying to exploit me or otherwise abuse me (it helped that i'm a white guy and a US citizen so they can't hold immigration/visa stuff over my head).
i hope this is helpful to at least someone considering a phd out there.