Why did the demos (people) start to organize uprisings against the nobility?

The nobles had many privileges and rights, so they could use the people for their own enrichment. The nobility set the size of the duties, used the population, in particular the peasantry, to work on their lands. As a result, the peasants found themselves in a disastrous situation: they did not have their own land to grow crops, earn money, but they had to settle accounts with the nobility. All this led to uprisings, growing discontent.