Honest answer: it's not as easy as you think. The print fees you pay to play a movie are INCREDIBLY high. I worked a 2nd run theater in high school. In the mid '90's it cost us between $1000-$2000 a week just to get the prints from a studio.
At the time our tickets only cost $1.50 a piece. We had to sell anywhere from 650+ to over 1300 seats just to break even on that part of the deal. We only had about 200 seats in the theater and M-Thu nights were dead...we'd be lucky to have 40-60 people (single screen). And that was just the print costs. You still had to pay for employees, electricity, equipment, real estate, heating/cooling, ect. That's where concessions came in to play. There were many weeks where we had crappy movies that we actually lost money. We made up for it on others, but overall it was incredibly cutthroat. You were at the mercy of the studios for prints. Because of ticket sales we were limited in choices and often couldn't afford to get first run or popular films to boost the ticket sales.
There's a reason why many small town cinemas are operated by larger groups. Independently they are not an economically viable entity. They can be supplemental though if you can trade prints in and out with your other theaters. Plus you have volume concession pricing that you get through your mega screen locations.