I read this article and the comments. www.bbc.co.uk/news/business-22002530
It is not unrealistic that the human race will be extinct one day, especially since the sun is probably finite.
There was a comment on that page that refers to Mike Judge's film Indiocracy - suggesting the problem is that stupid people are breeding more than intelligent people because smart people are more responsible. The film is a comedy but the commentator says 'it's bang on the money on what's happening at the moment'.
I actually found myself agreeing. Most of the intelligent people I know have as many children as they can afford (which is one or two maximum).
AIBU to think this?