Planets can become entirely inhospitable to life. Planets themselves have lifespans. Earth herself has in the past suffered near misses, e.g. 90%+ extinction events. It took billions of years of evolution to produce us, the only species ever to exist with the ability to reason about, prevent or ameliorate large extinction events (such as those caused by asteroid impacts), effect conservation management over evolutionary timescales, and even potentially to revive extinct species or propagate earth's lifeforms beyond the solar system and into a continuing timeline.
It's anti-conservationist and I think immoral to promote the view that anthropogenic climate change and the ongoing biodiversity crisis is about our fate alone.