Why did Hu Bayi abandon his son?

Hu Bayi didn't abandon his son, but Hu Bayi disappeared. Hu Bayi is a character in "The Ghost Blows the Lamp in Konoha". His son is Hu Tian, and Hu Bayi disappeared in an expedition. There is no way to watch his children grow up. In the end, the child was raised by Uncle Wan. The main line of this drama mainly revolves around his son Hu Tian looking for his parents who have been missing for 20 years, and embarked on the exploration road of overlord burial. Among them, Hu Tian explored his life experience all the way, and he was a designated expert in the geomantic omen of the stars.