I don’t understand how it’s possible to generationally take “...massive debt to pay for entitlements that will eventually have to be paid for by their grandchildren”

The debt is there but really it’s a wealth redistribution/accounting problem. Someone owns the other side of the debt, and considers it an asset so in aggregate it’s a net zero.

The problem really is that debt that can’t be paid won’t so are we really just looking at some sort of large scale accounting trick where someone is more wealthy than they actually are.