UBI is not guaranteed to make the majority of people better off. Its effects and consequences are highly dependent upon the source of revenue from which it is financed. You have to know the source of revenue for UBI and how other prices in the economy react to it in order to determine if it will make the majority of people wealthier or poorer.

If UBI is funded via taxes on labor and capital rather than taxes on land, it will subsidize landowners and banks and allow them to charge higher rent and make more from mortgages. If the price which a family pays for shelter, rent, and mortagages increases in proportion to the rate which their income increases from UBI, then will not actually be any wealthier.

Society will actually be much poorer, as we would be redistributing money from productive workers and entrepreneurs to unproductive landholders and lenders who were able to capture the increased public spending through higher land prices and rent.

It's basically not possible to do that without making those things cheaper somehow. Convert the entire US federal budget to UBI and it is around 10k per person. Healthcare alone per person is already 9k. Housing is maybe another 5k. And this is before those things get more expensive as people consume more of them.