Non-bitcoin transactions are just a couple of entries in various databases. Mining bitcoin is intense number crunching.
HFT makes the financial markets a tiny bit more accurate by resolving inconsistencies (for example three pairs of currencies can get out of whack with one another) and obvious mispricings (for various definitions of "obvious")
HFT makes the financial markets a tiny bit more accurate by resolving inconsistencies (for example three pairs of currencies can get out of whack with one another) and obvious mispricings (for various definitions of "obvious")