1. Why are you assuming a massive population crisis when that isn't the case virtually anywhere?
2. That flood won't occur because you are assuming that automatization is going to replace the vast majority of jobs while population somehow increases.
3. Easier said than done.
4. So you will allow a lot of misery just because people aren't citizens? I thought I was the bad guy here.
5. The basis that trading illegal items or activities becomes one of the only outlets of gaining income beyond the basic income.
6. It will rapidly shift the money supply and have an unknown effect on a huge number of industries which primarily rely on high income earners while employing low income earners.
7. "given 3" what does that mean? You assume that those things add up to being even close to what a basic income would cost. There is a reason why virtually no economist on the planet of any reputable school thinks this is a good idea.