The simple reason you do your best not to let any legislative "negotiations" drag on forever. A bunch of rich guys have been telling Manchin how awesome he is for months, and every time he goes on teevee and is an asshole, they butter him up even more.
We aren't ruled by wise and benevolent people, for the most part. The best you can say is, "Members of Congress, they're just like us! (only richer)."