as someone who suffers similar experiences, especially ocd related to nail-biting and rumination/adhd rabbit-holes, something i've adopted is a shift in attitude: i decided a while ago i was going to stop punishing or shaming myself for what my brain finds interesting or worth pursuing (ie: the "rabbit-hole", the fixation, the current dopamine drip).
most of the time my rabbit holes are pragmatic and related to a hobby, skill, or educational/learning.
but sometimes the rabbit holes are escapism -- and instead of telling myself this is wasted time, i've tried to develop a more cooperative relationship w my feelings and my brain --the brain, the body, perhaps the "spirit" was in need of rest, and it recuperates in ways that generally are creature comforts (maybe reading or Netflix binges or video games and chess or sleeping for me, YMMV w.r.t. "meaningless" activities).
this has mitigated a lot of the existential dread i previously would experience, especially in how i relate to perceived "wasted time".
obviously this is my experience and i do not mean to imply the above anecdote as being a prescriptive change, but the existential dilemmas i'd find myself in due to whatever neuro divergence i demonstrate, have gotten a lot less frequent, and i find myself enjoying these experiences, and therefore appreciating my rabbit-holes more and more over time. or rather, appreciating my brain, and my experiences overall.
i've tried the preventative and/or tried fighting "against the current", so to speak, and it always left me exhausted, depressed, despairing, lamenting, and floating back the way i came, so i kinda said fuck it, built myself a raft that i strengthen over time, and just navigate the waters as they come.
edit: i realize i drifted away from the original topic -- i've had the opposite experience with the internet. while it has contributed to me consuming otherwise "meaningless" content from time to time for no other reason than wanting to be a couch potate, i have benefitted from the ease of access to information in such a crazy fucking way, especially with platforms like youtube (and forums, or aggregators) -- i mean we effectively have libraries in various forms and abstractions at our fingertips. yes it means accessible vectors for distraction, but man -- it's single-handedly the one tool my life has benefitted the most from using -- and that includes some of the listed pursuits involving networking, relationship building/socializing, my career, my "real-world" interests and experiences, good, bad, and everything in between.