MRS has already turned down $1 million to walk away: he is in this death business for more than just the money, but a little cash always make him smile for a brief time. MRS is a dedicated agent of the euthanasia conspiracy: euthanasia means everything to him. That may be why he even killed Terri's cats.
Not to mention starving and dehydrating his own parents. Necromania...I knew someone into that. Scary stuff.
How many millions is Terri insured for? But you're right, he's in it for much more than the money. I still think he wants to cover his tracks for attempted murder.