Don't you have a math error?
0.0005 x 20,000 = 10 BTC not 100 BTC
That doesn't diminish your point about the large volume perhaps being wash trades of insiders selling to themselves to pump up the price and volume.
Yea, you're right. I accidentally used 0.5% instead of 0.05%. They aren't paying astronomical fees, but you can clearly tell it's wash traded.