Uhm, people don't even need to speculate on how much other hodlers hodl.  A certain someone already openly stated that Trendon Shavers alone cost him 1.6K BTC, and that's after deducting "interest" received.  So the principle amount is even higher.  No need to read up past posts either.  People can also make educated guess simply based on the year that they started accumulating BTC, assuming that they hadn't lost it through the million ways that you can lose your BTC.