That's far too simplistic and cannot be taken seriously. One of the first serious issues you'd have to consider is migration from other countries to your model

That's far too simplistic and cannot be taken seriously. One of the first serious issues you'd have to consider is migration from other countries to your model country with basic income. There's billions of people out there who'd happily live on basic income in some first world country and I'd absolutely encourage them to do so, given what the first world's riches are built on (but I digress...).