Why did slaves in the French colony of Saint-Domingue revolt?

Saint-Domingue, now the country of Haiti, was one of France's most profitable colonies in the eighteenth century. Wealthy French planters grew rich off of sugar, cotton, and coffee that they produced using slave labor. Because of their reliance on slave labor, the white French colonists were greatly outnumbered by slaves. In addition, because the labor was so intensive (especially the production of sugar), slave mortality rates were high, and new shipments of slaves were needed regularly. Some slaves also escaped to the mountains on the island and formed maroon colonies. There was also a class of free blacks, called gens de couleur, who faced discrimination despite being free. Many worked as artisans or domestic workers and were not given the same rights as free whites.
In 1789, the French Revolution broke out, and the National Assembly’s publication of the Declaration of Rights of Man, which declared that all men were free and equal, greatly influenced both slaves and the gens de couleur who helped lead the Haitian Revolution. Toussaint Louverture, a former slave, emerged as the leader of the revolution. Louverture helped unite both slaves and free blacks to demand freedom and equal rights. The Haitian Revolution was the most successful slave revolt in history. Because slaves and free blacks greatly outnumbered whites on the island and because of events in Europe, including the turmoil of the French Revolution and the rise of Napoleon, the revolutionaries in Haiti were able to secure independence and officially declare independence as the free nation of Haiti in 1803.
https://library.brown.edu/haitihistory/5.html