I suspect that the vast majority of people, not knowing in advance whether they will either end up in a permanently vegetative state or be diagnosed with cancer, would prefer that any resources that would be spent on PVS care be reallocated to cancer research—or some similar enterprise that has the potential to help human beings who might actually recover.
"Rational Rationing vs. Irrational Rationing", The Huffington Post (2010-06-23)