what do you mean beginning its from earliest know mining or just new miner
if new miner than maybe a lot people that not sold the bitcoin maybe just testing the miner or something else.
is from the earliest mining maybe the sold some to cover up the electricty an hold the rest unless they have free electric but still
maybe one or two people not sell any single bitcoin they have
i think your right . new miners havent sell yet because they are new and not enought bitcoins are mined to sell for profit and to pay their expenses but for the old miners they already earned alot of profit from selling some of their mined bitcoins and they wouldnt sell the newly mined bitcoins . i dont think there are people that never sold thier bitcoin , maybe the owner of those addreses that havent move their btc is non existing already .