First of all his leadership of Fateh and the PLO worked to concentrate power in the hands of his particular opportunist clique. He undermined the Palestinian liberation movement throughout it's history. He undermined, dominated, and excluded the radical sections of Fateh which rejected collaboration with Zionism, who threatened his rule. His agreement to exit Lebanon directly led to the massacre of thousands. His signing onto the oslo accords and his creation of the Palestinian authority with its security and police force built for direct collaboration with the Zionist state and repression of Palestinian resistance signed the west bank away to Israel. Yaser Arafat is the direct cause of decades upon decades of failure of the Palestinian liberation movement, and his legacy continues to haunt us to this very day with the traitorous Fateh party and Palestinian authority.