Great home theater sound systems with subwoofers are cheap and readily available now. They make the home movie-watching experience dramatically better than it used to be.

Home theater sound is often/usually better than the theater, if you actually put any effort in. Many theaters can't do proper Dolby Atmos with height channels. You can install a setup at home for ~$1500.

Adds complexity, cost, and clutter. Meanwhile, the living situations of many (most?) people forbid it; no big-kicking subwoofers in apartments and condos, and you're probably keeping the volume at polite levels.

And for all that, it's likely still not up to par with a theater, unless you geeked out on a dedicated theater room.