Don't worry, there is so many buyers waiting to by the dip, it will be bought up!
Nope,you are wrong,there aren't that many buyers.However,I'm 100% sure that Faketoshi doesn't have 820,000 bitcoins.He probably has 800,000 BSV of whatever forked altcoins they had(I don't even remember the names of all the BCH forked shitcoins).There's nothing wrong to sell them and dump their price.
i also seriously doubt if he has that much of either BSV or BCH. not only because it still costs a lot of money to have that much amount of these altcoins but also because these coins are clearly without a good long term future and the creators of them know it better than any of us. mainly they made these coins to make money from them not to have the coins!
in fact i believe that they use these coins to pump then take the profit and invest it back in bitcoin...