Jonathan Haidt's book The Righteous Mind is good on this. He provides a lot of evidence that show that, most of the time, people don't change their minds when they argue about politics. They find evidence to support what they already thought, and then blast away at each other. People who don't care much either way might be enticed to join one side, and occasionally diehards switch, but most people remain in place.

The primary purpose of political argument is probably communication among groups of supporters, and secondarily attracting those who haven't picked a side. It is rarely to change the minds of the opposing group. The latter almost never happens because of temperament, upbringing, social bonds, and habits, like where people go to get their news. Social media, podcasts, etc. reinforce this further by allowing people to curate their information sources. Even Google search results encourage it by feeding people information that is "up their alley".