So it seems like the top 5 pools control over 50% of the hashrate:
https://blockchain.info/poolsWhat's to stop these 5 from getting together and messing with the block chain ledger for their benefit? I understand the miners in these pools are not necessarily controlled, but what if the Top 5 pools changed fees instead of -1% to +1% just for mining with them on a corrupted blockchain? Basically bribing everyone to accept their way?
there is such a pool - and it's happened before - it just doesn't work for long, as they run out of money or confidence.
GHash.io? They never actually performed a 51% attack, they just reached a dangerously high amount of the hashrate. There has never been a 51% attack on the Bitcoin network.
if their changes do not meet the rules that nodes/merchants also have then those blocks would get rejected in seconds..
its not about hashrate.. its about rules and whats acceptable to the symbiotic relationship of the network
a block of data is not accepted simply because more hash power was used.
Mining pools only control the hashrate for now anyway. It's not like in the inception of Bitcoin, satoshi said "hey Antpool, so you're going to get 16.8% of the hashrate, and BTC.TOP you're going to get 13.3%"...
If they attempted a 51% attack, miners would just move to the numerous other pools available which were not participating in the attack.