AFAIK, the PoS in ethereum is structured that it is extremely hard to ignore a stake (you're vulnerable to slashing if you do), and that you are only vulnerable

AFAIK, the PoS in ethereum is structured that it is extremely hard to ignore a stake (you're vulnerable to slashing if you do), and that you are only vulnerable to slashing if you cheat (not if you are merely offline, at which point you just forego any rewards). Counteracting this requires a similar or greater amount than a PoW chain would require for similar effects (where a 51% attack can also simply refuse to build off of a particular miners blocks, thus effectively stopping their reward).