Go on insane car chases and die spectacularly. The hospital bill tends to get expensive when you have lots of money.
Aside from the safehouses you acquire during the game, there are no other properties you can get. It really doesn't fit with the story, anyway. It's a talk of individual revenge, not one of criminal domination like the two previous GTA games.
I was just thinking that when my overall account money jumped from 954,500 to 900,001 after I jumped out of a helicopter over Algonquin. There must be some sort of percentage ratio or something that the hospital takes.