I know that my well armed home is no challenge to a group of well armed, well trained, and highly motivated MS-13 gang members. I doubt if the rich folk in the hamptons are going to fare a lot better.
I think you’re right. A “safe room” is foolproof only if you spend 100% your time there. Go outside and take a dip in the pool, and those millionaires will be as vulnerable as the rest of us.