There are a few reasons that Einstein declined the offer to be the president of Israel. Firstly, he was already 73 years old at the time and felt that he was not physically or mentally fit for such a demanding role. Additionally, he was a pacifist and did not want to be associated with any political or military actions that may have been necessary in the role of president.
Yes, Einstein was offered the presidency of Israel in 1952 by then-prime minister David Ben-Gurion. Ben-Gurion believed that Einstein's international reputation and Jewish heritage would make him an ideal candidate for the role.
Einstein did have ties to Israel, but not as strong as some other Jewish scientists and intellectuals of his time. He was a supporter of Zionism and believed in the establishment of a Jewish homeland in Palestine, but he did not have any personal or familial connections to the country.
In his response to Ben-Gurion's offer, Einstein wrote, "I am deeply moved by the offer from our State of Israel, and at once saddened and ashamed that I cannot accept it." He went on to explain his reasons for declining the role.
The offer to Einstein was ultimately declined, and Chaim Weizmann, a chemist and Zionist leader, became the first president of Israel. Weizmann had previously been the president of the World Zionist Organization and had played a significant role in the establishment of the state of Israel.