Jews are optimists. There was never any question about that since Abraham took his first steps as a Jew. God told him even then that the glass was always half filled. Abraham understood that the journey upon which he was to commence was one that would bring benefit to him and to his progeny.
Almost immediately Abraham found trouble. He had left the big city for the desert. He had left the confines of a place that he had known for a wilderness. He married a woman who was barren. His first son, by his handmaiden, caused enmity between his wife, Sarah, and with Hagar, the servant.
He lived among barbarians, awful people in Sodom, Gomorrah, and two other towns. He became involved in wars and in politics. He struggled over water rights. When finally in old age he became a father, he almost killed the new son because God had told him to do just that. His wife died and he had to find a place for her burial.
Life was difficult for Abraham from the time that God told him that life would be better. And things did not improve for his son Isaac, or for his grandson Jacob. Indeed before Jacob reached hoary old age he had believed his favorite son was killed; he suffered famine, and resettled in Egypt with nothing but dreams of what might have been.
Yet God had said that the journey for the Jew was one of benefit. And we never forgot that promise. From those early days we worked to change the world. From those early days we accepted the difficulties that life brings with the faith that we could make a better world for ourselves and for all people.
Since the time of Abraham we have struggled, but the struggle has always been worth the effort. We always lived with purpose. We never believed that life was meaningless. No matter what happened to us, we always believed that there would be an End of Days, a Messianic Period. We always believed in the force of the mitzvah, the idea that every act does change the world.
Other nations have become great and disappeared; we still exist, and only because of two words in Hebrew (a few more in English). God told Abraham and every Jew to journey out to find a better world.
Perhaps that is the secret of Jewish endurance and Jewish success.