I found this post useful in understanding this phenomenon: https://www.offmessage.net/p/how-liberalism-sabotages-itself

The basic gist is that the left is too generous in its understanding of others' intentions, assuming good intentions from all actors long past the point where that's rational.

They're also coopted by their donors and the thinking they can't be mean to their "colleagues", look at all the democrats saying they're "waiting for the republican party to come back". They want the same status quo they had in the past because it serves those already in power there, they can continue to collect donations and salaries if it all stays the same without doing much work.

Look at how desperate they all were to leave DC and go on vacation, these people are not serious and they don't think there will be any consequence to them.