Peik Lin's father is a kind man, one of the few men we see who is also trying to climb the social ladder, but not grotesquely.
However, he isn't cutthroat and seems to understand his position and why he is where he is. The "Chinese-educated son of a Hainanese immigrant," he knew he had to work harder to prove himself in the meritocracy that is Singapore (2.16.3). He has raised his children well: all three of them work for the family business and lunch together frequently.
Though his primary motivation is curiosity, Wye Mun looks into the Young family to ensure they're "good enough" for Rachel (1.16.124). He takes Peik Lin to meet Dr. Gu, a man who knows much of the history of Singapore as well as the wealth. Dr. Gu wisely chastises Wye Mun for "always chasing after the money" (2.16.47).
In the end, Wye Mun opens his home to Rachel after she has been burned by Nick's mother and grandmother. He serves as a father Rachel never had, "You've been through a lot, Rachel Chu. I'm glad we are able to help […] You are welcome to stay as long as you like" (3.15.74).