Whomever said that altruism was acting out of concern for the welfare of others misconstrued altruism.
It’s a lazy interpretation of the word, most likely by self centred non altruistic persons.
The meaning is the other way around: It’s acting as if the self isn’t the centre of every concern.
From the French word autrui simply meaning “other people”.
There are no bleeding hearts or Venn diagrams required.