In the words of the comedian Ron White:
“You can’t fix stupid”
You, and he, are probably right. I've brought a couple of liberal leaning friends around - but it has taken literally years of steady effort. Basically you have to:
Always be sane/rational. Don't give in to wild exaggeration or angry discourse - even when they do.
Point out whenever they go off-topic (as liberals do) when they start to lose an argument based on facts. Liberals will always deflect the argument onto a side issue, make emotional appeals, or even resort to personal insults/attacks. Don't respond to these in kind, and don't let the discussion go astray. "Are we done discussing X, have you conceded that I am right on it and would now like to talk about Y?" "Your personal attack on me (or X) leads me to believe you have no real facts to add to our discussion on Y." etc. Be prepared. Almost any substantive discussion with a liberal will end with them trying one or more of techniques.
Always point out that for any supposed "cure" for some real or imagined suffering they see in the world, someone else must suffer. (lost money, resources, freedoms) Ask them if they would like to be the oppressor of these other people.
Know that you are first going to have to "un-educate" them on just about everything they think they know about how the world, economy, government, business etc. works. Because they are a liberal, they've accepted the indoctrination crammed down the throats of unsuspecting students in our public schools and most colleges. Use real-world examples of both the successes of captialism and the private sector, as well as the failures of socialism and fascism. The source material here is almost limitless. Don't over do it and inundate them.
The best thing that can happen to a liberal - that will help you convert them back to reality - is if they get a real job and/or something happens to them that makes them accept real responsibility. When you actually have to work to put food on the table, or take care of an ailing relative, etc. it changes your outlook from the great sounding ideals of liberalism/socialism. You start to see the real consequences of those ideals, and how they lead to fascism. They need to see, first hand, their resources being confiscated for others, their freedoms impinged. It is kind of cold, but they need to have their rampant idealism crushed. A little idealism is a good thing. Too much in the real world leaves you open to abuse and manipulation by those with less than lofty motives.
I claim a couple of successes at converting friends. However, I must also confess a couple of losses too. One I knew I'd lost when he succumbed to a terminal case of PDS. He just couldn't stop regurgitating all the hate-filled drivel about Sarah Palin. He couldn't even tell me why, with any specific examples (based on fact), he didn't like her. When his Facebook posts became full of vile hate speech towards her I finally completely disassociated myself from him. The irony here is he is a homosexual, and you'd think he'd be a little more sensitive to prejudice and hateful speech and insults. Par for the hypocrisy course with terminal liberals I guess.
A second friend has married a liberal woman and I'm afraid he's more taken with her charms. ;-) Sadly he is also allowing himself to be sucked into her world view. He actually thinks obamacare is a good thing. He voted for obama, and is planning on voting for him again. His transformation is so sickening I just can't be around him anymore. Nice guy, his wife is a nice person, but they are just so short-sighted and eff'd in the head I can't take it.