@jindra Two things:

1. I don't mean the people who happen to be in it at a given moment, I mean the people who make up society in it. That is a changing membership, but that's fine. You don't immediately leave it when you leave the country and you don't join it by arriving on holiday, roughly speaking you're a member if you are contributing meaningfully (within your means) to the life and health of the people who live here.

2. My life did not develop and does not exist in a vacuum. It has been enabled by this country, the people in it and the economic and social framework built by the people here before me. I can choose to acknowledge that debt or repudiate it, but to ignore it would be dishonest. If I acknowledge it, I owe that society my efforts to contribute to it, to help the other people in it as I can, and to defend it against people who would destroy or degrade it and replace it with a society where fewer people have lives that are free and safe and enjoyable and with fewer opportunities.