Inflation is not flat. When the money currently chasing luxury items like exotic cars or fine art switches to rent, produce and other basic goods their price will rise, it just will.
Real inflation does not require an expansion in money supply because inflation is not flat across all areas of the economy.
That is not the case.
If under UBI, which is reallocation of capital, luxury housing frees up it will not mean the uber rich move away and now the rest of us enjoy more selection without any other repercussions (though that will happen at first to an extent), it will mean they'll relocate to less expensive properties, thus chocking the market from both sides.
Real inflation does not require an expansion in money supply because inflation is not flat across all areas of the economy.