Is there a Heimlich Manoeuvre for cluelessness?

I recently went to a meeting with a new contact wants a fee for a project. The site plan is completely unviable, and anyone who thinks it is is delusional, or completely unfamiliar with real estate development in the developed world. (E.g..: It has no parking and probably requires over 300 spots.) I tell the guy this, and you know what he says?
In his windowless 8x12 office filled with boxes, behind an unpainted masonite door, he waves off the inconvenient fact and says, "Yeah, but how much?" I tell him 5-6% as a rule of thumb, and then he asks, "Yeah, but how much is it going to cost to build?"

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