Pls see Chesterton’s Fence. If you think borders serve no good purpose and that nobody is happy about them, it’s because you’re ignorant about borders and haven’t bothered to read anything or think about it at all. Lots of people want borders, and for better or worse, lots of people are happy about them, which is why they are there. You don’t get to take borders down until you understand and acknowledge the reasons they were put up.

Which state are we discussing? Can you point to a legal document or constitution for a country that defines the state’s purpose as keeping people happy? Maybe one exists, but I’ve never heard of that anywhere. I think in most countries, it’s your own responsibility to keep yourself happy. A lot of countries will, however, try to keep it’s citizens safe and try to protect the economy, and borders are seen as one of the tools to help meet those ends.