I attribute it to idiocy, but not on the part of Germany today. Sibling comments have already pointed out that a shutdown of nuclear was already decided in 2011 and that you can't just reverse that decision on a whim. I want to add that the shutdown is a culmination of over 60 years of lobbying, first by the Green Party when they were still single-issue radicals in parliament, then by environmental groups like Greenpeace. I like to believe that their intentions have always been good and noble, but to prioritize nuclear over the real polluter (fossil fuels) has always struck me as idiotic. It didn't help that the media constantly painted the search for a final resting place for nuclear waste as an insurmountable crisis, and of course Fukushima basically did the rest.

>you can't just reverse that decision on a whim.

You definitely can when your own existence/security is under threat.

In such cases, you can override people's idealist wishes since keeping borders defended and citizens safe, fed and warm in trouble times is more important to maintaining a stable economy and society long term, than rolling with the idealist fantasies of not using nuclear energy that people wished for when times were good.

But 30 years of not taking military/defense and energy self sufficiency seriously, is costing the EU taxpayer greatly now. It's a tragedy of the commons.