Another reason was the sheer brutality of the sugar plantations meant that slaves often survived for only a few years. Thus when the revolt began almost all the Haitian slaves were Africans who shared languages, a warrior culture, and other cohesive factors that made military cohesion easier than, say the USA where many slaves did not have the training or knowledge due to birth and upbringing on plantations.
Also it is worth noting that there were numerous revolutions all over Central and South America during this time. Haiti was earlier than most, but by 1830 most of Central and South America had revolted against European rule. Many of these newly freed countries outlawed slavery, and after 1807 the British began shutting down the Atlantic Slave Trade itself.