Why were the members of the third estate dissatisfied with their way of life under the old regime?

The Old Regime tried to consolidate power in France to the point where only they would have a say. The Third Regime made up at least 90% of French people, and they were, therefore, outraged. Plus, the First and Second Estates (clergy and nobles, respectively) often sided together because they were the "upper crust". Each Estate had one vote, so the views of the First and Second Estates were often passed. Again, this only represented a fraction of France's population, so the Third Estate was rightfully angry and demanded more power. Plus, they often had to deal with the brunt of the economic turmoil (famine, poverty, etc.)