I think you are only referring to a single cryptocurrency.

Just Marketing .. Not Decentralized .. That's what people usually see about Dash.

It is Normal to minipulate Markets ! Make people sell .. That's how speculators work .. They make people dump and sell the product at cheaper price then buy from them and sell it at higher price ..

How you deal with that right ? You just sell .. You don't ned to be aggressive in supporting it just sell at high price then buy again at the end you will make much more money than those long term investors.
Why do they fail in dumping it ? Let me Answer this qustion.

As For the current rumors which actually refer to Dash ..

One day Dash was DRK ( Dark coin ) It was really decentralized going the same path through bitcoin but now I kind of agree with it not being decentralized but I don't agree with it being just marketing

Back to the question .. whyb Dash didn't dump ? it is MasterNodes .. Those old invstors might see dash as a new digital currency so the demand rise but wil be as successful as bitcoin ? That I can only leave it for time to answer.

Now Let's how to benifit from speculation
Now let's do it on Numbers .. Let's say someone bought MasterNodes when it was 17$ Which is 17,000$ For a MasterNode .. but a speculator bought only 1,000 Dash and wasn't intersted in a longterm investment
Two Months Later .. The price reached the summit 58$ .. Now We have 58,000 $ for the speculator and the MasterNode made 16 extra dash which is 928$

The MasterNode Only invests .. He only sold half of those 16 Dash .. So He now has 464$

The Speculator Sold it all at 58,000$ and Started dumping it .. Made those rumors every where so people can sell him at cheaper price .. he then bought other 1000 dash at only 35 $ which is 35000$

So Our speculator friend mad more than 20,000$ in a month just by speculation and sending rumors to every body .. Interesting right ? Making more money than those olds who only know to keep