You mean why they didn't filibuster the one reconciliation bill on the senate which was literally the only chance they had to stop the administration?

Because the government does a lot of stuff, like say, feeding poor people, providing healthcare to seniors etc. And when the reconciliation bill came through, trump was still broadly popular.

So, what you're asking is for the Democrats to hurt a lot of people until the Republicans simply changed the rules to remove that obstacle, which they have the power to do.

So, I guess the better question is, exactly how did you expect the Dems to stop these things? Be specific.