Because change is painful. Taking it to the extreme of metaphor, change is death. When we change, either as individuals or as a culture/society, a part of us, a part of the past, a part of who we were in the past….dies. And a new part is born. Birth and death are the two most painful things we face in life. As a society, that is related to the birth and death of ideas and ways of being, the birth and death of societal paradigms. Change…hurts.
Conservatism (political and social) in its essence is nothing more than trying to stop change. Progressivism in its essence is bringing as much change as possible to society. Change is pain. That is why bravery, the bravery to openly and honestly face pain of change, is a Progressive trait…and not so much a Conservative one.

In order to stop the worst of Climate Change, for instance, we have to change nearly every aspect of the ‘American lifestyle,’ from the personal scale to the grandest of scales. Every aspect of our economy, the way we work, the way we get to work, the way we grow our food, the way that food is brought to us, the way we go to get that food at the store, the way we build homes and cities and suburbs, the way we power and use power in our homes, the way we are entertained, educated, find mates….
The ways and reasons we wage wars (or don’t) and all of our foreign policy.