If you limit your attacker to GPUs and pretend that ethash asics don't exist, then yes Ethereum is harder to attack than Bitcoin
In real life though it's significantly cheaper to attack Ethereum than Bitcoin https://t.co/9zP09I9t16
RT @paddykcl: Everyone is worried about 51% attack.
For Ethereum and Bitcoin, I'm much more worried about:
- Selfish mining (25%+)
- Some form of bribery (in or out of band)
- Feather Forking (big miner bullies smaller miners to follow in line)