These are all good points.

But unlike in the films, Thorin doesn't seem to have got to know Bard before, while he seems to have assessed the Master of Laketown pretty well.

And I don't think he trusts the Men and the Elves to leave the Dwarves either part or the whole of the treasure, once he gives in. He knows the weakness of his position.

(Or rather, he knows the weakness of his position, before he loses perspective, as you point out.)