Is a 51% attack a fatal security risk for bitcoin? - Quora
Yes it is fatal. Bitcoin owners will lose value over and over again everytime it happens because of their fear.
Why risk our hard-earned money to some chance that it may/may not happen?
Everytime it happens, bitcoin value will drop, and we will lose value. Every time, we have to move our money in and out of the bitcoin because of our fear. The financial brokers love to see that because every time we move our money, they get a percentage of our money. The implication of 51% attack is bad. Values will be lost over and over again. In the end we will be slaves to the biggest financial institutions: the banks.
Why don't we convert our currency to Peercoin? As simple as that. I am just starting to.
PEERCOIN is shielded from 51% attack, and it encourages decentralization by giving minting incentives. It does not consume much electricity too because it uses a genius Proof of Stake system. (No one will be motivated to kill the network if they have 51% of the stake in it. It will be stupid to stab himself.)
Their design has successfully slowed down the blockchain size increase to 0.6GB after 5 years, compared to 110 GB for bitcoin. This will also make bitcoin more centralized in the future because a full node will need a lot of hard drive space.
Read this forum discussion to understand more about PEERCOIN: (At first I was also skeptical)