Earlier quoted context omitted.
I don't know much aboute Etherium but wouldn't he be owner of a substantial fraction of the blockchain at that point? If so, he can't sell it without tanking the value so hard he'd never be able to get a decent fraction of its "worth".
Selling ~7M ETH is easy without affecting the markets too much. Kraken and Poloniex each do an average weekly volume of 3M ETH on the ETH/BTC pair: https://cryptowat.ch/poloniex/ethbtc/1w If he spread the sale over 10 weeks he would only increase their weekly volume by 10%. That's not even talking about alternate ways to transfer his wealth out of ETH (eg. approaching his billionaire friend: "how about you sell me th…
And again off exchange block/bulk sales tend to go for lower than market price. They are rarely, if ever, executed at market price. So most probably he will have to offer 100k ETH, 4.8mil, for a ~4 mil mansion.