I think it's only selfish if there's a self that gets patted on the back or seeks to be a newer, better self. We're made of whatever we're made of. That a self-concept can arise says nothing about some supposed quality of existence but more about the causes of its arising, namely ignorance and other factors. Self is an attitude
It is made of many parts and conditions, not the other way around.
Mudita, sympathetic joy, is something to read further about as well in this arena. I find the presence or absence of mudita for me will tell the bare truth about my state of mind at the time, no matter how I may feel
Essentially, everything that Dechen Norbu said
And Chogyam Trungpa has some very poignant insight about this as well, like someone else mentioned.