Basic income cannot be set by the "cost of living". Life isn't free. In a world with 10 billion people and only enough food for 5 billion it is impossible to give everyone enough income to eat. You can only give everyone a share in the produced food. In this case, everyone would have an income of half a meal and then have to trade with others.

Money and shares are just a more efficient form of rationing the production proportional to ownership. Basic income is nothing more than guaranteeing every individual a share in the means of production.