Why did Jiang Ziya help attack Zhou? What was he like in history?

Jiang Ziya was a common man at first, but he was also a man with a heart for the whole world, and he was proficient in Zhouyi gossip. It was not until he was sixty or seventy years old that he succeeded in his later years and became a small official in Chao Ge. Later, he found that Zhou Wang was dissolute and heartless. Later, when he heard that Zhou Wenwang of Xiqiao was a man with lofty ideals, he wanted to quit his job and go to Xiqiao to assist Zhou Wenwang. With his understanding of the world and mastery of the Eight Diagrams of Zhouyi, Jiang Ziya helped to cut down the Zhou Dynasty. He is an ordinary old man who is praised by the people, but in fact he is not so mythical. After Jiang Ziya left Chao Ge, he did not go to Zhou Wenwang immediately, but lived in seclusion in a small village in Xiqiao, doing something for the local people from time to time. Jiang Ziya also knows pharmacology and fortune telling, so many people are willing to impress Jiang Ziya with some unpleasant things. Slowly, Jiang Ziya became more and more famous in Xiqiao, and it reached the ears of Zhou Wenwang. Zhou Wenwang is very talented, so he wants Jiang Ziya to help him. Jiang Ziya is a very clever man, but his talent is not appreciated by the world. In his early years, he remained unknown, worked hard and understood the sufferings of the people. I didn't do anything until my hair turned white. And he is a very honest man, because of his own experience, he doesn't complain. When he lived in Xiqi, he fished by the river. The hook is not only vertical, but also has no bait on it. He doesn't insist on many things. Even Zhou Wenwang is willing to find Jiang Ziya mountain, Zhou Wenwang personally carried Jiang Ziya's sedan chair all the way back to Xiqiao with Jiang Ziya, in order to ask Jiang Ziya for help. Later, Zhou Wenwang appointed Jiang Ziya as Xiqiao Buddhist and trusted Jiang Ziya very much. After Zhou Wenwang's death, Jiang Ziya helped Zhou Wuwang to attack. He took the world as his own duty, and called the heroes of the world to gather in Xiqiao to jointly deal with Zhou Wang. In fact, Jiang Ziya's greatest contribution to Zhou Wuwang's success was to conform to public opinion, and those who won the hearts of the people won the world, and the attack on Zhou was bound to succeed.