That being said, being a post-doc with independent funding (e.g. a national fellowship) is perhaps the best gig in academia, except that it can't last. You can actually spend all the time on research a PI wishes they could, and any leverage people have on you is not financial. Burning bridges could still hurt you of course.
Having been around many universities, I've seen a number of grad students who believed in academic universal ideals (e.g., the professor as a brilliant and benevolent citizen of the university microcosm) get blindsided by imperfect reality -- when they have the misfortune to be on the receiving end of someone else's mistake/wrongdoing, were powerless, and were not able to find anyone who would help them.
But I don't mean to discourage people from pursuing a PhD. This is just one reason for advice you've already heard, about the importance of finding a good advisor, who'll guide you through the process, and have your back if/when anything goes wrong. (Actually, in all the cases people have told me, it seems the student's career would've been saved if their advisor had had their back, and/or had enough influence to get the department/university to fix the problem. One other student came close to getting scrod, but didn't, because their parent was a noted academic at a top university, who could not only give good advice, but could also have their back, and simply make a phone call, like a good advisor.)
Changing to any new job is hard, but changing Ph.D. advisors/labs/schools/etc. can require you to restart your dissertation research again essentially from scratch.
Ph.D. programs are basically lengthy gauntlets of flaming hoops to jump through to get a meal ticket which is unlikely to get you an actual meal, because of the pyramid scheme. Though like many ordeals, if you manage to survive then you will probably be able to overcome other challenges in the future. You will also teach yourself a lot of things and probably meet some interesting people.
As one of my wise mentors put it, having things not work out with an advisor, even if people have a sense it was the fault of the advisor, marks a student as both "having had their chance" and also "damaged goods".
Unless their department/university facilitates the move, or they already have great publications (great enough to get past the "damaged goods" suspicion).
Regarding awareness of how the system works... While everyone has some shared sense of the systems of graduate studies and career development, an individual probably doesn't have much information about instances of wrenches being thrown into the works, especially not outside their own department or university. (Though they might hear rumors about a particular department elsewhere having cultural problems, and they've formed superficial impressions of a number of other professors, from their behavior at conferences or in faculty meetings, but that's about it.)
Also, I'll speculate it's possible that there's an element of survivorship bias: you don't get to be a professor without a lot of hard work, but also bit of luck in enough things going your way. Wronged grad students, on the other hand, tend to quickly disappear from professors' environments.
https://www.chemistryworld.com/news/university-of-hawaii-res...
(Warning: gross bodily injury.)