It’s not a contract, because the parties involved didn’t all get a chance to agree to it before hand.
Everyone gets automatic entry and can leave any time they want. If they decide they don’t agree to it there’s nothing keeping them from shrugging off the good graces of society. I think that’s pretty fair.
I was in a very bad spot once and one part of it was due to the so called social contract and the demands it put on me as an individual but when I tried to exit the contract I got forced in ward psychiatric care which kind of negates your argument of there being a choice.
Now a days I still have some issues with the social contract but have other things to live for and have managed to come to terms on how to live with it.