With proof of stake, having that money is enough to vote and you don't need to spend or waste it. In fact, you get paid for having that money sitting in the account.
It was worse with PoW in theory. Just because you have tons of mining equipment doesn't mean you have a stake in the future of the cryptocurrency.
The thing about crypto is that the majority hashrate/stake gets to decide what is an "attack" and what isn't. This behavior isn't a bug, it's a feature and it's what separates crypto from fiat.
With PoW, sooner or later the attacker will run out of money. When they stop paying for the hashrate, their votes all goes away, they don't get extra points for being the top miner at one point in time. With PoS, getting a majority means that your majority will actually increase over time unless someone actively decides to burn the cash necessary to stop you. The longer the community waits/debate over it, the harder it will be to remove the "attacker".
Yes with PoS it's harder to remove the attacker. But the attacker also stands to lose far more money than the attack can possibly be worth.