Why Don't they Try Reality

There's a story on the internet today about an "eminent" Australian scientist who is predicting human extinction within 100 years due to overpopulation, climate change, etc.  It's a story that gets repeated over and over again.  Remember Malthus, whose name gave rise to the term Malthusian?  He predicted that overpopulation and resulting world hunger would destroy most, if not all, of humanity.  Malthus thought that catastrophe was imminent, but that was 200 years ago.  Today, there are about seven times more people on the planet than when Malthus wrote his first polemic, and there is more food per capita produced than was the case all those centuries ago.  Since that time, there have been a whole series of scientists who have predicted that we would run out of resources, that we would run out of food, that we would destroy the planet, and all other manner of disasters.  We're still here.

Just think of where we were twenty years ago.  At that point, we were told that the world was running out of fossil fuels.  Today, because of technology changes, there is an abundance of supply of these fuels.  Climate change was the big bugaboo for the last 15 years; we now know that increased carbon dioxide has had essentially no effect on the climate.

The reality is that the worldwide population has stopped growing rapidly.  In many countries we will soon see a decline in total numbers.  The threat of climate change is also not real.  Indeed, all of the supposed horrors that this "eminent" Australian scientist fears have been shown to be hollow threats.

Why is it that the purveyors of doom won't try reality?  What is it that drives them to predict disaster?