Especially for rich people and for
consumption (not investment) it looks
obvious to me that they have negative time preference for consumption. Why? They could choose to consume all their money today to whatever they want (business jets, charity, space travel etc) and live rest of their lives in poverty if they face negative interest rates on their assets. That's what a positive time preference looks like. Of course, even when rates are negative, the rich people choose to live comfortably also in the future, even if their total consumption is slightly smaller. And as the wealth has been concentrating during the last decades more and more to the wealthy ones, the interest rate needs to reflect more and more the time preference of the wealthy ones. You want to get higher interest rates, you need to reverse the wealth concentration.
(All of the above is completely without source or further arguments or detailed analysis available, just my thoughts.)