[MRM]

You may very well be able to limit the harm he does to himself by working with his paranoia and playing into his requests. I once took a call from someone who was supposed to be a potential client but who turned out to be very mentally ill. She had some sort of paranoia complex, conspiracies, radio implants, the whole nine yards. I had some experience with people like this when I was a prosecutor and the older lawyers in the office had given me some practical advice on handling them.

I tried to talk her down a bit and direct her energies in less destructive directions by acknowledging the basis for her paranoia and suggesting courses of action that she could believe would protect her while not being destructive. She actually responded well and ran around town doing eccentric but not dangerous tasks. Eventually her actual psychologist got in touch with me. I explained who I was and what I was doing. To my mild surprise, the doctor agreed and told me to keep doing it. SHe said that the only way to engage with someone who is irrational is to accept their irrationality and to work with them on that basis.

It makes sense. Think about it for a minute. You are not going to convince someone like that they are wrong. It's not a matter of explaining facts to the person or being more convincing or showing incontrovertible proof. None of that helps because the person is irrational. Appealing to an irrational person's rationality is counterproductive and wastes both time and energy. Arguing with him will just make it worse and he will cut you out of his life.

What you might try is taking your dad aside and tell him that you understand the scope of the conspiracy and you'll work with him to keep him safe. If he wants to withdraw all his money, see if he'll allow you to hold it, or get it into a safe deposit box or somewhere else that it will be safe and keep him satisfied.

Definitely contact a mental health professional and get advice on what you and the family can do to work with him. I seem to recall some old movie where one of the old relatives thought he was Teddy Roosevelt and kept charging through the scenes shouting "Bully!". The family treated him as though he was the retired president and all was well. It won't be that easy in real life, but we all have our own delusions and depend on others to accommodate us. It's all a matter of scale in a way.