I comment when knowingly being uninformed because the resulting discussion is what helps me understand the topic better. The result of this, looking back on my comment history, is that I can come across as a bit of an asshole who's often wrong. That is why anonymity is important to me online, because my posting here is not really indicative of my real world behavior. It's a safe place to challenge ideas and opinions, and I feel like I've grown and learned a lot from it.
This is my long way of saying, maybe other people have different purposes for posting than you.
Commenting to learn is orthogonal to doing so in a way that "can come across as a bit of an asshole". The first tends to make Hacker News better. The second more than negates any benefit.
Have you considered the harm you cause by posting with confidence when you are secretly aware of your own ignorance? The behavior of the average human is to take confident-sounding things as truth, even if they consciously try not to. You might be coming off as an asshole due to the harm you're causing like this, and could reframe your posts as asking for more info and not just saying random things to get a response.
This is my long way of saying, maybe other people have different purposes for posting than you.