Ok, let’s assume people don’t work, robots or AI do all the jobs. People just do fun stuff.
Government brings in UBI because people need to pay for things such as food and housing. Traditionally governments have taxed work and spending to bring in income. They spend this income on a combination of government projects and services (education, defence, health etc), maintaining the government machine (civil service, MPs & associated costs) and supporting those without an income from work.
In a world without work and a UBI, they need to support everyone.
Which they can only fund from tax receipts, which can only be raised from work and spending…
So they tax spending - result is people buy less because their UBI no longer goes as far. Government decides to increase the UBI to encourage spending in order to raise more tax revenue, but their current income is down due to reduced tax receipts from reduced spending. Catch-22.
As no one works they can’t tax workers, they have to tax those that supply AI services. Which makes supplying AI less attractive to those suppliers. They find that whatever revenue they generate they end up paying a hefty whack in tax so government can pay for the UBI. They increase the price they charge for AI services to businesses, who in turn put up their own prices they charge the consumer. The government then needs to increase the basic UBI to enable people to pay for goods otherwise they have a declining income from taxing AI and production as demand falls due to lowered spending power.
Oh, and if the government are using AI to replace the civil service and they’re being charged more by AI companies each time they increase the tax take from those companies in order to fund the UBI for non-workers, then the hamster has moved into government, hasn’t he?
I may have got the wrong end of the stick as I’m not an economist, but it seems to me that it’s impossible for a government to produce income for tax purposes from its own endeavour, it needs outside receipts to bring in any income.
If 99% of the population are detached from creating any wealth at all, they’re just engaged in spending money handed to them by the government which was raised by taxing the 1%, then, well, were doomed to failure, aren’t we?