Because Germany will invade Paris again before they would let them do that. A small country budget like Greece is not the same as a huge country budget on the eu economy.

It’s because the debt is so high and the cost of pensions with an aging population will increase that ,raising taxes and cutting pensions and everything the central bank could do within eu rules wouldn’t be enough. The current cumulative debt is large and so is the annual deficit.

The problem is that they have too much debt and they can’t just ignore it anymore. They can complain but they have to cut spending somewhere or increase revenue. Now they can raise the retirement age for everyone. Or they can take the money from the billionaires. But that still doesn’t get you closer to lowering the deficit which is very high well over 100 percent of GDP. That means the protests are really just complaining that France doesn’t have enough money but you can’t keep the spending going as is without a lot of drastic cuts. All you can do is cuts now or kick the can down the road and hope something changes. Or just default on the debt and say fuck it.