Wrong question. I think you meant to ask "Why can't I stop reading HN?"

I suspect very few people obsessively look at HN all day. The site doesn't have any inherently addictive quality, especially when compared to other social media platforms that actively try to steal time and attention. A few people might spend too much time scrolling through HN out of boredom or procrastination, they should ask themselves why they choose to do that rather than looking for something "addictive" about the site.