The real problem is not the debt, but the social instability caused by the measures taken to address the debt.
If you see the state as an institution to allow the rich and powerful to extract resources from the rest of the population, then it's all fine. Just take out some debt to give a contract to your nephew, then pay it back by devaluing the currency
But debt also accumulates, and usually faster than GDP growth. Until debt servicing starts eating your budget. Which is a slowly encroaching killer
I find it difficult to draw conclusions just yet. Yes, Germany is under-investing and that hurts. But with another 20 years of hindsight it might look like the lesser evil