I confess to watching way too many movies in theater (feel free to face punch me now), though last year I ended up net-positive on watching movies (after paying for myself and my girlfriend) because we often go with friends, I buy the tickets and get reimbursed by them, and since I have an AMC membership (only $12/year, and worth the rewards if you go often) I get $10 for every $100 spent, so I actually profited.
That being said, I alway bring water with me, and buy the largest popcorn (free refills!) and share it with multiple people, so I don't spend much (and I hate 3d, so I go to the cheaper 2d movies)