The PhDs being discussed here are those in the humanities but the points apply mutatis mutandis to those in the exact sciences as well.
Professional suicide is what graduate students are already committing on a daily basis as they confront the reality of a Ph.D. that cannot be turned into meaningful work, and the looming default on what are often hundreds of thousands of dollars in loans.
Professional suicide is what adjuncts are committing each year that they spill out their time, energy, and spirit in an endless, pointless and ultimately fruitless quest for security.
Professional suicide is what Ph.D.s contemplate when they have to painfully and laboriously attempt to reinvent themselves for a non-academic position, for which the Ph.D. is appallingly expensive, slow, and imprecise training, when they are already often in their mid-40s or beyond.
Professional suicide is what Ph.D.s face when they discover ten or more years of their peak earning years have been lost in the black hole of a graduate program that yields nothing in the end but devastating opportunity costs.