Food for intelligent thought : BTC mining revenue down ~95% from peak. Likewise, either Bitmain (et al) have sold twice as many miners as they ever had in 2018 vs all years prior, or someone is utilizing a lot of Secret ASIC. PoW chg is pain management.
Follow up: Bitcoin clone has 51% attack vulnerability worse than first thought… double jeopardy as can’t be fixed without a sustained crash in the price or hard fork. Bitcoin miners could go in for the kill in 2020