I think it's still because the whole market is falling.
Therefore, the DASH has also fallen with it. This is not because the DASH is a shit coin, but the DASH is a top token.
You're wrong, Dash has in 2018 performed much worse than Bitcoin (the benchmark) and many other coins.
Just look at Dash's drop in relative market cap from #3 to #15. The "whole market" isn't falling either; just look at Ethereum Classic for example.
Stop making lame excuses and deal with the fact that Dash is the worst performer in the top 20.
Dash is barely a "top token" and will eventually drop out of the top 20 forever.