some authors argue that proof of stake is not an ideal option for a distributed consensus protocol. one issue that can arise is the "nothing-at-stake" problem, wherein block generators have nothing to lose by voting for multiple blockchain histories, thereby preventing consensus from being achieved. because unlike in proof-of-work systems, there is little cost to working on several chains. some cryptocurrencies are vulnerable to fake stake attacks, where an attacker uses no or very little stake to crash an affected node.