I’m not sure where you came up with 3/month @ $12 each. The actual numbers could be wildly different, I don’t think it’s safe to speculate so broadly.
Also, while AMC is large, they aren’t the only game in town. They only control ~8k of the 40k screens in the US. You can bet that if moviepass is able to drive demand away from AMC they will cave eventually.
It's a quote from the CEO of AMC from their recent investor call.
"Fast forward to today, in March and April, MoviePass paid AMC $12.02 per ticket on hundreds and hundreds and hundreds of thousands of tickets each month, hundreds of thousands of their subscribers came through AMC theaters to enjoy our product. They did so at a frequency of 2.62 times in March and 2.75 times in April. Now, I took the calculator out and I multiplied 2.75 times $12.02, and I got to a number that was considerably larger than 995. So just as we were hearing that -- the MoviePass price point was unsustainable in August, we have the same questions today. And apparently we’re not alone in that view. Our doubts are now shared and articulated by MoviePass's orders."
Also, while AMC is large, they aren’t the only game in town. They only control ~8k of the 40k screens in the US. You can bet that if moviepass is able to drive demand away from AMC they will cave eventually.