Theatres don't just show new movies. There's something very special about being locked in a dark room with a big screen to watch Alien or Barry Lyndon. Older movies especially look great in a theatre and some of the magic is lost on a smaller screen.

90% of any content is crap but you're missing out if you like movies and you haven't seen Sinners, The Bone Temple, or NOPE (to name a few recent great theatre watches).

I regularly go to a nearby cinema that also shows older movies. Watching a movie like "Ran" (Akira Kurosawa) in a restored 4k version on a big screen is quite an experience. (Tickets are 10€ btw.) Often I go with a friend, but occasionally I also go alone. There's something about spending 2 or 3 hours in a dark room entirely focussing on a piece of art.