Addiction to Russian gas, over-bureaucratic system that's super inefficient with tax-money meaning most goes to waste, an ageing population hoarding all the wealth and burdening the welfare system, uncontrolled unskilled immigration further burdening the welfare system and pushing rents up, clueless boomer leaders not investing in innovation and capturing new areas of the economy, refusing to build more real-estate because environment further pushing housing up, politics based on ideology not reality, a clueless and arrogant voter base thinking everything is perfect and none of the issues above need addressing, will do that to you.
Though, that's most of Europe, not just Germany.