I had a biology teacher explain why bee sacrifices herself for eggs that aren't even hers:
if a eusocial-insect colony has only one queen, and she has only mated once, then the relatedness between workers (diploid females) in a hive or nest is 3⁄4. This means the workers in such monogamous single-queen colonies are significantly more closely related than in other sex determination systems where the relatedness of siblings is usually no more than 1⁄2.
They are closer related to each other than we are to our own children.