Why do I expect the privatization of space stations and NASA not continuing operating any ISS-like projects on their own to NOT save 1.5 billion USD every year.

why do I expect this will be a desaster both in quality and cost with an very expensive overall cost?

we already know how well privatization worked so far.

just to clarify: I am not saying the ISS will be sold. Instead it's near the end of its life and NASA explicitly no longer wants to upkeep any space stations