They have been doing it since at least 2016, consistently selling large amounts of steem in one go and flooding the market, thus dropping the value. The comments on that post by steemit have so much information people have gathered about what they have been doing. But about 11 months ago my other half stumbled across accounts where steemit were funneling STEEM and SBD off the platform and selling it off, and had been for years, it's a long post but he does name some of the accounts they used to sell from. They used to transfer the funds between a lot of accounts before selling so it was harder to trace back, but the beauty of the blockchain is that it is all there if someone goes looking. And despite doing this, they haven't entirely sunk it because the principle works, and there are enough people who want to trust and support it.

At least they are being transparent about the fact they are selling so much off every month. It seems like such a shame, because some of the earlier crashes in price match up with their big cash outs. I personally suspect that is why they changed how it works so more people ended up buying in, because they had so much to sell. Then again, I am here for the people, money was a bonus, but it did work for a while, unfortunately the people behind it either had no understanding of economics, or they knowingly ran it down. There are new people in charge, and they seem far from perfect still, but they do seem like they might consider taking on feedback, and there are people like @raj808 writing wonderful responses to steemits proposals with a positive focus on what can be done. There is still a swell of possibility, I don't know if the currency will ever recover to what it was, but there are enough people who want it to and are prepared to make the effort, and put themselves out there.