Also, I thought something like 40% of browsers run adblockers, and possibly a disproportionate amount in your demographics. That could explain the bulk if the difference.
Perfect for measuring raw HTTP requests, sure, but if you post a link to a brand new, zero-follower account you'll still get a few dozen bots that are doing link analysis against the Twitter firehose (well, a random sampling of it).
We have people in this very thread openly talking about deploying third party ad scripts that send their users on chains of redirects that they admit to losing track of, and the only thing they see wrong with this is that they can't accurately track their users, not that they very probably sent their users down whatever rabbit/shithole serving malware, miners or drive-by downloaders.
Online advertising is a disgusting wasteland and many people coming out of the woodworks in this thread, working in the industry, are knowingly, unknowingly or usually willingly blindly working to create this situation as it is. Dollar bills make for very good blinders, especially if it's your living.