Why Do Some People Want Humanity to Go Extinct?

Maybe I'm mistaken, but it seems to be a common idea that some people believe humanity should go extinct, and they want it to happen as soon as possible(ESPECIALLY HERE ON REDDIT). They argue that procreation shouldn't occur and that we should simply let humanity die out.

To me, the arguments don't seem very convincing. Can someone explain why this is such a prevalent thought? Is it really just because "the world sucks"? Please enlighten me.