Lu Yuanming initially undertook the conquest of the Skeleton Fortress because he had already experienced two tombstone hallucinations. According to Doctor Keson's analysis, this was due to his fear of death affecting him, and the land of skeletons happened to be where the emotion of fear of death accumulated. This was why he came to conquer this place.
Speaking of importance, the importance of the special block of dark matter was certainly greater.
In Lu Yuanming's perspective regarding priorities, the welfare of human civilization ranked above all else, on par in importance with his own family, and even higher than his own life. He would rather sacrifice himself to ensure the continuation of human civilization, just as he would protect his own family, for without human civilization, his family could not survive alone.
