This article seems devoid of facts. It starts off saying someone moved 25k Bitcoins to an exchange, prompting people to talk about it. You know what this article is talking about? Roger Ver amidst the Bitcoin Cash attack:
https://amp.reddit.com/r/Bitcoin/comments/7cefom/roger_ver_just_sent_25k_btc_to_bitfinex/True, this was certainly market manipulation at work, but the coins moving didn't prompt the drop itself. It came with massive social media FUD and a mempool spam attack. That was a confirmed case of a Bitcoin whale trying to bring down Bitcoin with his friends and failing. That suggests it's much easier to do in theory than in practice.
About 40 percent of bitcoin is held by perhaps 1,000 users; at current prices, each may want to sell about half of his or her holdings, says Aaron Brown, former managing director and head of financial markets research at AQR Capital Management.
I would like to know where he got his data. I know that there is market inequality, but I always thought it would be impossible to precisely quanitify because people can use multiple wallets with no traces of each other.
Asked about whether large holders could move in concert, Roger Ver, a well-known early bitcoin investor, said in an email: “I suspect that is likely true, and people should be able to do whatever they want with their own money. I’ve personally never had time for things like that though.”
They conveniently forgot to mention that while Roger Ver is still holding Bitcoins, he's rooting for Bitcoin Cash now.