On throwing out your back to be cool, and failing.
Democrats (well the leadership, not the voters as much) are the kid whose entire life revolves around what the school bully *might* say. Democrats are me in middle school getting a backache because I was terrified two straps were "uncool" (only dorks use a bag designed carry heavy objects correctly)
Democrats come in, listing to the side like a sinking ship as the heavy bag full of books slowly pulls them over, never realizing what made one strap so "cool" was having nothing in your bag: because you aren't some huge nerd who likes books.
Leaders have a responsibility to set an example, to project better values. When Democratic leaders let the criticism from the far right shape how they present themselves they normalize conservative and extremist vales. I wish they'd stop making this mistake.