Just guessing, but Alex's fortune relied on windfalls of income from various settlements from lawsuits. Instead of setting money aside or trying to live within average means, he spent money like crazy when he had it. He then needed to finagle more shady deals via lawsuits/insurance settlements to keep up with the cost of maintaining that lifestyle.
The houses, the properties, condos and expensive toys for the sons, the dogs, the boats, the various vehicles, employees to run things, etc. were requiring large, regular cash infusions . Add in the drug habit and it becomes impossible to keep funding. To make the situation worse, Paul's problems became a major drain on already scarce assets.
Instead of saying "Heck the kids are grown and in college, let's start unloading some of this stuff" AM tried to keep it going. I've seen families in my area go through this cycle, of course on a smaller scale. The big McMansion house, brand new cars and designer clothes for the high school kids, boats, RV's, expensive vacations, jet skis, luxury cars, etc. Then a few years later, the possessions are gone and parents are living in a nice condo. Downsizing, why couldn't AM do it?