You don’t lose out but helping or being a mentch to anyone.
I read a story (forgot which book) from the holocaust of a man who was saved by a goy. The goy warned him that the S.S. were in the building looking for him, and how to escape. Before he ran, he asked the man, why is he telling him this, and this man, who was the elevator man, said every morning, you would tell me good morning, while all the other passengers acted as if I didn’t exist. When the man broke his arm, the yid inquired about it, and had a doctor, look it and have it taken care of properly. This yid was saved because he cared and acted like a
mentch.
It does not take any extra effort to be kind to someone and wish them a greeting.