Please provide evidence tying miners to operating also masternodes and please provide evidence that such combo is directly responsible for Dash price decline.
It's actually more incumbent on you to demonstrate that they're not since the protocol encourages hybrid mining as the most profitable configuration.
It is not me supporting thunderjet assumptions, and it is not me needing to provide evidence for those assumptions.
The ball is clearly in you and thunderjet corner.
If you can't find any evidence then this will just remain a base-less assumption, a personal opinion that is lacking evidence.