There's a thin line between selfishness and self-love. Sometimes one may not realize the difference until it has grown to a certain level.
Selfishness is holding one's self interest as the standard for decision making while Self-love means not settling for less than you deserve.
As long as your interest affects that of another, it's selfishness else it could just be self love. While we were children, our parents told us a story of a tortoise and the birds. The birds were invited to heaven for a feast, and the tortoise who couldn't fly went to some birds to borrow wings to help him fly. When they got to heaven, the tortoise in his cunning nature told the birds that it was proper for them to be addressed by names, so he called himself "All of you" and the rest of the birds gave themselves a different name. Each time food was presented, the tortoise would ask, "to whom is the food presented?" And the person presenting the food will say "All of you". Tortoise would turn to the other birds and say, the food is actually for Me, so he kept doing so while starving the other birds. When it was time to return, angrily the other birds collected their wings. Tortoise who couldn't fly down, jumped from the sky and got his back cracked . This was a story to help us realize how dangerous being selfish is.
When one's interest starts to overshadow the wellbeing of other people, selfishness is in play. Self love is built around one self, not accepting a standard below that which you deserve