This story is a sobering reminder.
Real estate can be stable, but any asset is susceptible to concentrated and unavoidable risk, such as flooding, market crashes, or policy changes or shifts etc which can tell negatively on investment.

 The devastating death of his fathers financial life highlights your significant lesson:
  1 Diversify across different industries.
 2 Spread physical assets across the globe.
 3 Insure as much as possible

 It's Unpredictability that defines risk not just volatility.