51% is no posible?
Hm.. Ok let´s get CEX.io
almost 30Ph/s
With total Network HashRate
Is about 40%. But We need to remember that Network HashRate is jumping. Sometimes it´s going down or up. There is too big chance to make 51% attack. ( With small invest You can make it) Now let´s say that someone have a lot of bitcoins or money ( for example from SilkRoad or from "Hacked" exchanges or just bought them
) now small invest with 50% of Your bitcoins to take down some pool ( diffrent than cex.io) and who have more HashPower? Taking down some big pool or 2 small pools is so easy and You can do this with arround 5,000 - 10,000 $ invest. and if You know what are You doing it´s can bring You about 60% of your investment. It´s risky and not for everyone but YES IT IS POSIBLE.
Confirmations on BitCoin Network Take to much time... It is going worst and worst....