I agree. Pretty much all internet sources are inherently biased due to response bias, so there's no fixing that without talking to such people face to face (which is a bit hard in my area).
But if you aggregate enough data you can at least start to see some sort of prevailing trends and sentiments. So I am open to better sources and some biased/compromised forums are still better that choosing to be trapped in an echo chamber. I have browsed around on other comments sections from news sources and the results unfortunately make Reddit look like a think-tank.
Sure, the average American who identifies as conservative just shows up every 4 years and hits the R without giving it much though. Thinking about them doesn't really give us much either.
I think /r/conservative tells us a lot, even if it's not representative of the constituency. The President is driven by memes and is extremely online. The "vibes" in /r/conservative (and on X, The Everything App) are extremely relevant, because these are the audiences Trump plays to.
We need to stop reaching for the easiest data source just because we're desperate for a data source. There's a reason great research is hard - mostly because it requires stupendous effort (and funding!) to get reliable results.