Governments already have systems to identify who is a citizen. You can't Sybil attack birth certificates and naturalization paperwork because they're issued by a trustworthy entity[0]. Worldcoin is trying to reinvent ID cards for the sake of... IDK, becoming some kind of ancap alternative to a state bureaucracy?

Also, not everyone is going to accept UBI as a substitute for labor. We already see artists complaining specifically that AI art takes away the fun part of the job. The entire LessWrong/EA memeplex[1] assumes that the benefits of AI will be so obvious that humanity will tolerate the imposition of a new technological priesthood responsible for aligning AI to humanity's collective interests. Worship us and we will make Star Trek a documentary. This is like if you took all the worst parts of Christianity and all the worst parts of authoritarian Soviet Communism and mashed them up in a blender.

[0] Bracing for the inevitable UHM ACKTUALLY comments about ballot stuffing in third world countries

[1] Short for MEME comPLEX. A series of ideas that tend to be adopted together because they are self-reinforcing.