How did deficit spending lead to social unrest during the French Revolution?

Deficit spending created huge problems within the economy. As a result, Necker put forth the idea of taxing the upper class, something that created immense tension and conflict among the First and Second Estates. This idea was so abhored that the upper class forced the King to dismiss Necker, but things only got worse. In response to the conflict, the King was forced to call a meeting of all three estates, during which time, they could list and air their grievances.