No, I don’t feel I owe the world everything because I am Jewish. I feel that I owe hakaras hatov to America for granting me freedom to practice my life as I wish. I am grateful that others went to bat for freedoms that they didn’t need so that I could have them. I don’t want to deny others the freedom to practice life as they please with the same benefits because of different choices we make.
Let me give an easy example: my company has a multipurpose room at headquarters. Every day, there is a mincha minyan (plus a maariv minyan when applicable). Now, imagine a group of muslims wanted to pray there also and I said “No, company property should not be used for religious purposes. Unless they are mine of course.” That’s the equivalent of what you are saying – give me freedom and deny others.
Not all the benefits of marriage can be granted in a contract (especially financial things like social security).
Truth is, this is a non-issue. In a few years gay marriage will be the norm. It already is in Canada and nothing has changed there.