You can be absolutely certain you want to do a PhD and still end up with an abusive advisor. Certainty doesn't need to have anything to do with the state of your mental health with your PhD. What we should be stopping is these tenured advisors who literally get away with screaming at their students.
A PhD should be what you make of it. If you want to work for 3 hours a day and have it take 8+ years, then so be it. Sometimes you do need to do that if you have dependents, for instance. You can always secure your own funding and/or TA. But it shouldn't be an excuse for a boss to squeeze unlimited hours out of you for less than the price of an hourly technician.
A PhD should be what you make of it. If you want to work for 3 hours a day and have it take 8+ years, then so be it. Sometimes you do need to do that if you have dependents, for instance. You can always secure your own funding and/or TA. But it shouldn't be an excuse for a boss to squeeze unlimited hours out of you for less than the price of an hourly technician.