The Democrats are just there to give the illusion of choice. When there are only two guys in a race which one of them has to win, how do you ensure you always pick a winner? You buy both sides, of course. There are a handful of progressive Democrats in Congress. A small handful. The rest of them are Republicans who don't like to look mean/evil. They have the same pay masters the Republicans do in Israel and the corporations. So of course they were going to cave. Have the shutdown go on long enough to pretend like you gave a shit and then pull the rug before the holidays so nothing actually changes. Average Americans will continue taking it up the ass while the rich/wealthy continue to get everything.
Outside of the few truly good actors like Bernie or AOC, the entire Democratic Party is behind Americans losing their healthcare. Chuck and them will go out and say they're voting no and want to keep the shutdown running, but in reality it's just the typical rotating cast of villains. Senators who aren't up for election for a few years have to take the PR hit so Chuck and the rest can play pretend. This slow march towards fascism and kleptocracy only happened because the Democrats were willing participants in it the entire time.