I don't know. It depends.
One of my siblings is incredibly annoying with the boundaries he sets. I do see him as selfish. But...he has to be I think, because otherwise his own mental health would suffer. He's been suicidal in the past, so I'd rather he was selfish and alive, than the alternative.
My mum used to be incredibly selfish. The impact of her actions on those around her were horrendous. She was abusive throughout my life. However, in her older years if she'd ever recognised what she had done, actually looked outside of herself, she too would have ended her life as I don't think she could have been able to bare what she saw.
Selfishness is basically self-protection. I don't like it because it neglects others needs and often causes people to act in ways that harm or neglect others. But, it keeps people safe so it serves a necessary function for those that display it.
In my opinion, when people 'set boundaries' it's often about asserting their needs ahead of others, if being selfish. But sometimes they need to be for their own sake.
This life is hard.