Nope, just the contrary. In a PoW system, once you own the hardware, it cost nearly nothing to attack any eco-system that uses the same algorithm. As shown by many PoW altcoins attacked to death.

In a PoS system, acquiring enough stake to attack will cost you astronomical amount of money, (you can't really hack the stake, since it's illegitimate stake and can be rolled back by community action). Then once you acquire the stake, you could only attack one particular PoS system (which you own a majority stake in, why would you attack it? it's illogical).

Therefore, ZERO PoS system has been actually attacked so far.

I'm not sure why people ignore the fact that tons of PoW altcoin has been attacked, and ZERO PoS altcoin attacked so far, and still have the audacity to claim PoS is less secure.