I've seen that betarigs rental and it could easily just be a troll with a GPU farm trying to stir things up.  Just because Darkcoin profitability sucks doesn't mean it's being mined by FPGAs, yet.  The amount of hash on Darkcoin could easily be explained by those who left DOGE and LTC, as you've gotta remember most GPUs easily do 2x the hash of Scrypt on X11.

I will agree that Darkcoin sucks for plenty of other reasons, though.  It was basically instamined due to the unfair block reward algorithm.  The 1000 coin requirement to be a masternode is primarily what's driving buy demand.  Once investors start realizing they'll never see a ROI and that legitimate merchants will never have anything to do with the coin, it's gonna dump harder than Auroracoin.