What critical lesson did your early investment in Alexander's Department Stores teach you about position sizing?

Buying Alexander's Department Stores out of bankruptcy at roughly 8 dollars per share represented 35 to 40 percent of my personal net worth at the time. The stock quickly rebounded to 21 dollars, and I sold for a quick profit. Years later, that stock compounded past 600 dollars per share because of the immense underlying value of its retail real estate. That experience taught me early on that identifying great assets is only half the battle; capturing their true compounding potential requires the patience not to sell prematurely.