You know who sacrifices himself to save humanity? Jesus. And, if you were an ancient Greek or Roman, Prometheus. Does that make Victor a god-like figure? Or does he just want to think of himself as a god-like hero? After all, Victor's self-sacrifice also includes the sacrifice of those he loves, so—work with us here—it seems more an act of inhumane, self-absorbed injustice than like love for humanity. In Frankenstein, Victor decides to be a hero in his own mind rather than preserving the lives of those he loves. Thanks, but we can do without that kind of sacrifice.
Victor wants to destroy the monster more out of a desire for revenge than any noble ideas about self-sacrifice.
Frankenstein criticizes the very idea of self-sacrifice as individualistic and selfish.