I personally think going closed is what is killing drk. The experts like AA are avoiding it and the whales did not react to RC4. Also markets will not form around closed source tech. There was a window to gain the support of the privacy community. Drk was leading that race.
Nothing is killing DRK.

It's a tiny and volatile market, currently filled with ADD lemmings, prices will fluctuate. Meanwhile clever people are getting on with building something amazing.
Anyone whining about the current price who isn't actively participating in some way to add value to the DRK ecosystem should really shut the fuck up,
it isn't anyone else's job to give you a free lunch.