The doctor's stern advice made Harrison reconsider the matter of the Four-Sided Treasure Tower.
It was true that he had invested a whole lot of effort into retrieving the tower, and even his health had been jeopardized. However, if he continued to cling to it, it would only expand his losses, and he would not have a chance to recover those losses.
Hence, the most reasonable thing to do now was to halt the mission. He had to admit and accept the fact that all his previous investments had gone