I work with a number of lawyers who are all ultra-liberal. They openly state that in terms of politics, the ends justify the means. They acknowledge the weakness of Obama and the corruption of the Clintons, but view it as a necessary evil to ensure that the Democrats remain in power to push the liberal agenda on every issue. They would sell the souls of their own children to ensure a liberal gets appointed to the Supreme Court.
Politics is about group identity. Hardcore supporters are impossible to change because membership in the group is the only thing that matters.
It's the same mental illness to believe that in order to gain freedom you must give away all your rights...
Watch the TedTalks video.
Tell them that the real power in this nation is in the hands of conservatives, and what they are going to get is not going to be a progressive Utopia, but will instead become a bloody civil war, which will be won by Conservatives.
Just as Europe's embrace of migrants is fueling a massive and bloody backlash, so too are Liberals pushing people to the point where they are going to snap and start solving problems with physical pushback.
You can also tells them that the one thing the US Constitution requires to be equal is the application of the law.
Therefore all legal services should be socialized and all lawyers should be paid by the government so that the rich may not obtain an unfair advantage by hiring a better Lawyer than the one provided by the government.
Apply their socialist preferences to themselves, and watch them disavow socialism. At least for themselves.