Taxes.
The tax burden in France, prior to the French Revolution, fell on the shoulders of the 98% of the population that made up the Third Estate. The First Estate consisted of the clergy, and the Second Estate was the nobility. Those two estates overlapped in some ways, because high ranking church officials functioned as a form of aristocracy too. And the two leading Estates colluded with one another to keep the system operating the way it was, with them having all the privileges and powers underneath the monarchy.
