Why did Jiang Ziya wait until he was old?

Jiang Ziya didn't meet face-to-face until he was old. This is because he never appreciates music, but no one appreciates his skill. Depressed, he was in back in the game during this period. Under the pressure of life, he herded cattle and sheep in the mountains and sold noodles in noodle restaurants. Although fate seems to have played a big joke on him, it finally gave him the best arrangement.