"Why haven't the earliest participants sold their Bitcoin, and some haven't even touched the coins in their addresses, considering the high price of Bitcoin?"
They are holding for so many reasons that me be personal to them, as we all know, bitcoin investment is a profitable thing to do and holding it over time will help in making this happen, though most of them never know this that bitcoin would have reached this far in market price, they only hodl to have an asset that could help them fall back to in the future, we can also make our own personal decision on bitcoin Investment to buy now and hold for the future to come for our own era of opportunities with bitcoin when we hodl.