I think the reason why we are getting such a drop is because people are sitting at negative ROI and it leads to these sell pressures.
Basically if you ever frequent the ethereum reddit most people on there basically dump their ETH for USD as soon as they get a payout from the pool because they need to pay for their 1080Ti and their electricity.
In a panicky market such as today, there are less willing buyers but the same amount of miners which dump prematurely and cause these huge 25% declines.
Also there are people who bought all their GPUs on Newegg and bought $20K worth of equipment and are paying interest at 20% APR which is like $300 a month in interest which isn't even enough from their mining profits. The same happened in 2014.
This is the perfect example on why people are not buying eth right now, they think those stupid people who bought thousands of dollars in mining equipment will have to sell their eth regardless of the price to pay the bills ehhe, funny is after they sold all their eth and quit mining then eth goes back to 1500 usd and up hehe and then those stupid people want to get back and mining and the cycle restarts hehe, they will never learn their lesson hehe
They must never sell their eth at his price, they should right now get a new loan and use it to pay the debts they have then as eth gets back to 2k plus usd then they can sell.
I agree with adaseb on this and do believe that miners have partly caused the value of ETH to trickle down. The selling pressure from all the miners definitely has to have some impact on value and the ETH devs and analysts know this, which is why they have also proposed the reduction of the ETH block reward.
At the end of it all, i'm just happy that the ETH dev team is still working hard on improvements. Surely one day this will all pay off.