Most people want to be right all the time. Most people on the internet have at least one public viewpoint that is perceived as wrong by someone else. Having your views challenged means you have to uncomfortably question yourself, and in most cases, people would rather defend their views even if they know that their opponent appears more well-informed, and maybe even more right.

You see this even more in person, when someone clearly lacks the information to back up their claims but defend them nonetheless. It is astounding how easily any of us can revert to the talking points that made us familiar with our viewpoint in the first place, instead of facing the facts that we are wrong and the other person - especially if we don't like them - is correct.

So in the end, the only real way to win an Internet argument is to have more people on your side than your opponent. Because at the end of the day, people are too set in their ways to let a username attached to a block of text change anything.