I see your point about how a reduction of options (of which a monopoly would be the degenerate case) could make something _seem_ compulsory. Eg, if you lived in an apartment building and therefore couldn't grow your own food, and there was only 1 grocery store within 50 miles you might as well have a gun to your head with respect to where you buy food.
So for the sake of argument suppose we equate a lack of options with compulsion. Still how does this apply to casinos? You don't need a casino to live or even to be entertained. Casinos have certain (state-granted) monopoly-like privileges to let them corner the gambling market in many ways, but they don't have a monopoly on anything critical like food, utilities, or entertainment.
Not trying to be argumentative or anything, just trying to see where you're coming from.