There're soft power advantages even for a Bill with an expected 1% chance of passing (GovTrack):

• It widens the Overton Window, challenging the neoliberal status quo.
• It organizes the 100+ organizations supporting it into a coalition.
• It forces Republicans to vote against a bill popular with Democrats, young people, and minority voters.

I'd rather have Democrats doing this type of strategy over sitting on their hands while they have no power. When it fails loudly in a hostile Congress it may accomplish more than a watered-down bill that quietly passes.

The right wing in America kept trying to pass anti-abortion laws for decades even though they were obviously unconstitutional, and here we are...