The worst things with regards to potential for unhealthy use, IMO, are passive feeds which require no effort on the user’s part. These simply become a timedraining habit. Reddit, HN, YouTube, any social media.
Many people have limited options in life. I grew up in a small northern town with very limited options. I collected stamps all winter. Was that 'unhealthy'? Because I learned some world history, did that 'redeem' it from 'unhealthiness'?
As soon as I got to college, the stamp-collecting ended. HOWEVER... I also learned -organization of large amounts of random information-. Guess where that led (hint: it wasn't 'unhealthy')