I would bet a lot of folks have been selling it over time. My wallet once held ~10 BTC for a few transactions back in the early days. I ended up with 5 btc left over that I rode the bull market with, selling half the position post bull run each time.

I kick myself for loosing the BTC my friend and I mined back in '09 on CPU time when it truly was worthless. But I was a dumb college student at the time and was simply playing around with it for a few days. I wonder how many BTC were permanently lost in this period.