An RSS reader really helped me with this. Over years, I found a good handful of blogs that I find insightful more often than not, and I can reliably find something in my RSS feed when I choose to look at it. The SNR is much higher than somewhere like Reddit and Hacker News, and the lack of an account and upvotes means that a big chunk of the dopamine fix is removed.
I would be lying if I didn't mention that I occasionally feel something missing: if I read an article that I think is insightful but wrong in some important way, I miss the pressure-release valve of being able to discuss it with others (Obligatory Xkcd: https://xkcd.com/386/). But I view this more like a compulsion than a legitimate desire, akin to someone with a bad diet craving sugar.
Sadly I find my attention span, even with a great read, has suffered greatly. I blame the internet, but maybe it's just me. It's very difficult to suffer through even a brief boring stretch now.
Same for me. Nowadays when I get bored and have some unproductive time to kill, I usually surf hacker news because I can't think of any other website to read as I quit other social media websites.
It's the same happiness/sadness you mention, although the lack of options on the internet has been turning out to be more positive than negative as I've been reading much much more.