Fellow ADHS person here - it's an addiction, it's not funny and it's close to a personal hell depending how worse it is.
If you can go offline and don't read HN or other news on the internet do it. It doesn't matter. Practice ignoring it. Turn off the internet - not forever but long enough every day that you realize in what situation you are in.
Why I'm saying such harsch things?
Because you (and me) are bullshitting ourselves here - we are consuming news, articles and comments and looking for some insights or new information but we can't link it to existing knowledge mostly or get sidetracked and lose control of our own directions, things to do because these are probably dull, difficult or boring and have consequences - so they cause anxiety - and it's easier and mostly automatic behavior to run away from them and just fill your head with random tidbits on here. I'm not saying this site is bad - don't get me wrong - it's just that reading for hours here every day will do you no good and won't improve anything.
What to do instead?
ADHD is all about executive dysfunction and working on improving things there can have a huge impact - medication might help but is no panacea - stress, anxiety, outright fear can also cause this behavior and make it worse (at least for me).
If you are in education or school go offline, go the lab, go to the lectures, meet other poeple in real life and work with them, this helps me a lot - take a pen and paper and work on problem sets or meet with other students - go from reading/consuming to writing/creating - make a shedule and be gently to yourself because you totally ignore it - but exercise getting better at it - exercise itself also helps, so does settings time-limits like stop working on something at a time, pomodoro technique and things like that.
This won't work very well or at all depending how deep you are in the trouble but if you catch yourself drifting away be gentle to yourself and practice taking control again.
Work torwards mastering yourself and what is in front of you, you may think it's not as cool or important but that is probably very likely wrong - do interact offline with real people, solve real problems and don't run away from it - face your shortcomings and failures and learn from them or at least avoid running away from your reality.
You need to learn to be honest with yourself and work torwards tackling realistic work in small pieces for things to improve. Going into writing/creating mode helps and also slows you down and puts real problems in front of you that are worth solving (or ditch the project because you had wrong ideas about that)
And be gentle to yourself it's okay to do gown the rabbit hole once in a while.