Well funny for us, in retrospective if you are that guy it must be brutal. He would be so rich now, it's pretty crazy to think about. This puts a lot of sense into these thinking that it's the end of the world and think they missed the boat. Just buy the big dips and hold.
I remember back in 2015 someone on Bitstamp placed a sell order of 30,000BTC at $300 which people were buying into, but it probably didn't shrink fast enough so that entity removed the sell wall and placed it at $275 which people bought in like crazy. This was just before the price tanked to $150 so it's not sure whether that entity ended up buying back lower or left the market entirely.
I miss these old times where these massive orders used to pop up frequently. Right now the only large orders you see pop up are on Bitfinex which I wouldn't be surprised about if it's all spoofing taking place. Nowadays whales either use the hidden orderbook feature to not publicly show large orders, or they make themselves look like a small fish by trading small amounts.