Bitcointalk extortion

DDos extortion is certainly not a new trick by the hacker commu-nity,. screenshot was taken from Profile of the Extorting Hacker.Although there are no known cases where pool operators abused their power, there have been several instances where the opportunity were present.

Bitcoin news roundup September 11th, 2016 - Deep Dot Web

Transactions cannot take place off chain without other layers of abstraction (lightning) as the ledger must be updated constantly to ensure double spends are not possible.