Problem is, paying for it with resources taken from the rich requires 10% of ALL the resources the rich have (not from their income, everything). Per year. Which would cannibalize most businesses in France in the process.

Leaving aside how moral this is or isn't, and the practical problems (like destroying businesses, and the fact that capital can't actually be sold at the price it is valued), it would block the state's ability to lend, which would immediately force the state to save 20 times more than what the protests are about.

Actually doing what every party is screaming they want to do (pay for the state using the rich's resources) would cause an immediate disaster. But this is France, that doesn't mean they won't do it.