It's always someone's first time properly paying attention to politics. There's no silver bullet argument, no specific citation of recent history that will immediately dissuade them of the usual civil-religion yankee-liberal brainworms. But you make the arguments and cite the history anyway, so that the next time Democrats fail them, they'll have enough context to see it for what it is.

It's cyclical, this happens a lot during a conservative president's first year or two; liberal politicians cater to the conservatives, liberal voters get angry at their own party for capitulating and working with conservatives, then when the election cycle ramps up the vast majority all vote lib again

tbf PSL's membership has surged in the past few years