Not necessarily true. I know a number of doctors who routinely have to sign off on cases because they refuse to participate in the family's wishes to kill a patient. Too few physicians stand up against this growing euthanasia movement, but heirs are just as much a force in the growth of this movement as the physicians themselves. Don't underestimate the childrens' desire that the estate survive their parents' illness as a driving force in these cases.
It was clearly the primary motive for the husband in the killing of Terri Schiavo.
well that and he wanted to run off with his new women and he was still married to Terri.