It's not the same, with inflation people still own the same percentage of wealth (people with 0 still have 0). With UBI the distribution of income changes, it's

It's not the same, with inflation people still own the same percentage of wealth (people with 0 still have 0). With UBI the distribution of income changes, it's minimum is no longer 0 but some hardcoded amount. So even if prices would adapt, you'd end up not only with different prices, but with a different distribution of wealth. In the extreme case, if the basic income was huge, everyone would pretty much be able to buy the same things, with the basic income set to 0, the distribution of wealth would be more exponential as wealthy people naturally get more and more wealthy and people with 0 stay at 0. You probably want something in between, with good incentives to work hard, but also good conditions for poor people and a higher velocity of money (if you give money to people with no money they'll spend a higher percentage of it, fueling the economy in the right areas).