There are significant problems with 3D on both the content and delivery side.
On the content side, apart from 3D blu-rays of action blockbusters, there isn't really any content. No TV shows or sports, and only a few video games produce stereoscopic content, and that was a brief that largely died out years ago. I would have thought that gamers would embrace 3D, but I guess the serious ones spend so much time looking at their screens that the eyestrain becomes a major factor. Indeed, one could argue for that very reason that 3D is better suited to shorter stuff like TV episodes. Series with sparse post-production effects, such as sitcoms or reality shows, would seem to be be ideal content drivers, but they haven't been. Also, stereoscopic porn never became a thing; even if you have a 3D TV, there's virtually no such smut to be found.
On the delivery side, consumers have been disinterested in 3D TVs, doubtless due in large part to the dearth of content. Also, 3D would really only be immersive in the biggest screens. Projection might seem more promising here, but one either has to get expensive battery-operated glasses that rapidly shutter lenses on and off (resulting in a sub-optimal presentation), or buy dual-lamp projection hardware for twice the cost, plus a particular type of reflective screen to watch 3D content with non-electronic glasses.
Roger Ebert used to say that all movies are 3D movies, because we unconsciously interpret them that way. When we're riveted by the drama of a scene, we don't stop to wonder why the actors' noses aren't jutting out in front of their mouths. I think there's a lot of truth to that.
Personally, I'd love to splurge on a dual-lamp projector plus special screen setup, and watch shows like Westworld and nature docuseries in 3D. (Maybe even an occasional presentation of adult ladies massaging each other, also.) But all that investment for a handful of 3D blu rays of about exclusively superhero movies (in the past decade, only a handful of drama films have had 3D versions) doesn't seem worth it, at least not at the moment.
The big hope for 3D outside of occasional action movies now seems to be VR headsets, where one doesn't need any additional tech to view 3D images. But even with affordable sharp and light screens at that size, there's no guarantee the tech will catch on in large enough numbers to drive a substantial increase in content.
