You spend "safety of your stacked money while having stacked a lot of money" it's a scarce resource as if you over spend it you lose your money. And the more money you have stacked the less interest you have into braking the currency as it makes you lose that money.

But it’s not a scarce resource you spent. As the author says, you can sign multiple, contradictory stakings.

Which can (likely will) make you lose all the stacked money.

The article addresses that in the section starting:

>>Therefore, once they have withdrawn their deposits, they are untouchable. This is the “nothing at stake” problem. There will inevitably come a point when a node is free to liquidate their entire stake and cash out.

And later concludes that, In order to know which is the valid staking, you have to already have a decentralized mechanism for ordering transactions, which was the problem to begin with.

But that's also true for PoW as you can use hardware which after an attack you can use for other things.

But you have to do new work (and a lot of it, requiring energy and time), compared to the trivial cost of generating another signature as in PoS.

You cant reuse the electricity you have already burned...