People are increasingly 'siloed into' their positions. I don't write to change the minds of our political enemies. Why do I write, then?
First, to arrive at the truth as best I can for my own edification and enjoyment. People like me like to figure things out and understand things. On our good days we theoreticians approach the blissful self-sufficiency of Aristotle's NOESIS NOESEOS.
Second, to provide argumentative ammo to those on our side. The choir DOES need to be preached to, so as to be fortified, and provided with tools for ideological combat.
Third, to persuade fence-sitters, people with open minds who can be nudged one way or the other.
Fourth, to let our enemies know that they will be opposed, and their lies exposed. Enough of us protesting loudly, but with wit, style and solid arguments, can have an intimidating effect on our enemies. Winning in a war requires intimidation. To intimidate is to induce a weakening fear in the enemy.
Fifth, because I'm a natural-born scribbler who takes great pleasure from writing and re-reading what he has written. The hunt for the incisive formulation that penetrates to the heart of the matter is a source of pleasure.