He had huge one-time income from a boom that was not sustainable. His budget planning assumed that this would go on forever.

Balancing his budget while counting on non-sustainable revenue was stupid.

The California government made the same mistake, only worse.

A piece of advice. Any large one-time source of revenue (inheritance, lottery, etc) should be treated as a small fraction of its face value. Because the best that you can do with it is invest it and take off a small fraction of the earnings each year. The worst thing that you can do (also the most common) is to expand your lifestyle to one which can only be sustained if you repeatedly get large cash infusions. When those fail to materialize, you wind up worse off than you were before.

Cheers,
Ben