When was the last time one of those thumb drives that are a few hundred Gigahashes found a block? I see people online selling them for several hundred dollars and calling them "lottery miners" when no one in over a year, as far as I know, has found a block with one of these devices. The lowest hashrate recently in the past year was in the Terahashes (TH) and not Gigahashes (GH). Also, how do we know that the miners who found a block a few months ago with THs weren't using a proxy and didn't have much higher hashing power being disguised by a proxy?