> I don't really care about the preservation of the human species. I'm going to be dead in the next 40 years or so, why should I care?

If most Homo sapiens had the same attitude, the species would have gone extinct since forever lol.

You can have any personal goal you'd like, but from the evolution perspective, the purpose of any living organism is to survive and to reproduce, hence preserving its own species. That's why.