The Principality of Sealand

While I think Sealand gets too much hype for effectively being 3 people living on an island. It does raise the question. What does it take to become a country?

There are significantly larger manmade structures than the Roughs Tower all around the globe. Would 1,000 people qualify for statehood? 10,000?

If you build an island (Dubai style) can that be considered a country? Does it have to be fixed in place? Or could a floating structure be considered?