The main reason for a sale of ETH is a panic among owners of scams ICO. They didn't buy an Etherium on exchange, they didn't mining it by spending electroenergy. They got it for free from naive investors.
The second reason is the lack of a clear understanding of issue rules and the final supply. Only blah blah.
Therefore I don't recommend keeping this coin in your portfolio. This asset today has low value to their holders.