The way to understand this, ask if PoS would have been bitgold released in 2009.

As bitcoin wasnt valued in 2009-2011, its value in USD was basically zero. Yet the cost of attacking the PoW even during that time was the cost of electricity which was higher than zero.

PoS, if it was released in 2009 instead of PoW, the cost to attack it would have been zero, as the price of bitcoin was.

There is a solution to this but none of the shitcoins have it implemented, instead chosing to give the creators all the power and majority stake.