Simply dumps from those ones who got free coins from bounties. Most of them dont know how hard devs worked to keep the project run, simply dumped to take money from free coins they received.
that you address to miners... there's tens of thousands of coins dumped. Btw I sold my airdrop long ago at 40k then traded the spread at least 3 times. The dump occured 2 days since that with the day before full of flat 38800