The biggest problem I had with the story was the complete idiocy of having 7 million in investments while making mortgage payments on two places. I just cannot fathom owing anyone anything if I had enough money not to. It’s utter foolishness not to have your primary residence paid off and all yours if you can, in my opinion.
It depends what you are using the money for, I guess. Smart investors can use the equity in their homes as a sort of low-interest bank to fund other investments. It can work very well, if you know what you're doing. A lot of rich people like to remain as liquid as possible.