My friend's parents are retiring comfortably from their long-term holdings in large cap tech names such as Amazon (in the ~$80s), Microsoft, Facebook, Netflix, etc., that they built over the past 20 years. They only invested in tech and had built substantial holdings over time. They owned a restaurant, worked hard but had no professional background in investing. They lived very conservatively and used their excess capital to invest it towards retirement. Of course they weren't all winners but they only needed a few.
This is a lesson to us all in (1) long-term investing (through the highs and lows), (2) concentrated ownership (which Mark Cuban often advocates), and (3) patience.
Hope we'll all be in the same shoes one day. Luckily we still have time on our hands.