If this did prove to be true then there wouldn't be much you could do to prepare for it except to get out while you still can. I'm almost certain that it's not true however. Even if he was Satoshi, why would he choose to dump his coins and effectively kill off his own creation in one fell swoop?
Well , some people would say that we have destroyed his great creation. (Banks getting involved etc)
The rumours have been floating around for over 2-3 months. If he was to really dump and run away, he could have done that during the market peak in December last year. Also, whales might be greedy, they won't be dumping for some cheap price considering the price would tank when the order book fills at least half... If the so called 1 million coins were true, and even before he sells, he should move his coins to any exchange wallet. That would create panic among the investors and would drop the price to at least $4000. A month back a particular whale wallet consisting of 23000 bitcoins were moved to another wallet, that resulted in a drop of few hundred dollars within hours.
Claiming himself as satoshi doesn't mean that he is satoshi. He hasn't proved cryptographically that he is satoshi by signing up the messages with the private keys. Hence, he is lying again and would lie forever.

Well if he were to prove that he was satoshi , Wouldn't others try to kill him for creating BTC?
Craig Wright isn't Satoshi Nakamoto,which means that Craig Wright doesn't have 1M bitcoins.
Craig Wright doesnt have 1 million bitcoins & he is not Satoshi.
/thread
you don't have to be Satoshi Nakamoto to own 1 million bitcoin, not to mention that Satoshi owning 1 million is something of an estimate and is debatable.
in any case OP is the only one who is making this claim so far! and it is a very strange one at that. not just because of debates about whether he is satoshi or not or if he even has that much bitcoin to dump. but because WHY would he even do that now! he is releasing an altcoin soon and every idiot on the planet knows if bitcoin goes down altcoins get dumped hard.
not to mention that a bitcoin price drop at this point triggers a massive scale FOMO buy of bitcoin and to do that people have to pull their money from altcoins. in other words if bitcoin drops, people rush to bitcoin and his altcoin fails in its first day

Yes i am the making those claims. It seems apparently that the "Bitcoin" experiment has gone wrong. (Blockstream now controls development of BTC who are apparently funded by Mastercard / the "FED" / and Bilderberg Group.)