Good question. There are several answers:
1) Ivy league types believe in social engineering, the kind that says we can win the war on poverty, the war on drugs, etc. This goes against human nature (and the wisdom of the Bible) in the sense that as the Bible says (paraphrase), We will always have the poor. Unfortunately, there is injustice in the world and no man-made plan can eradicate all of it man is a fallen creature. Ironically, the socialist Utopian plans for human perfection have actually created more misery imaginable (100 million dead in the last century from national and international socialism). But these Ivy League types refuse to give up on their blinkered idealism and continue to say, That really wasnt socialism and we just have to keep trying. In other words, they dont learn anything from reality.
2) Related to the first point is the idea that these professors have created their careers on this type of leftist thinking and they are not going to jeopardize what took them a whole life time to create they are not going to say I was wrong. (Actually some have like David Mamet, David Horowizt, Norman Podhoretz, Thomas Sowell, Whittaker Chambers, etc.) Many of these professors bought into the ideas of the Frankfurt School (communists) at a time when they themselves were students protesting the Vietnam War as part of the bigger picture of American imperialism. They knew they couldnt change the system from without through protests or violent revolution in the street but from within (through the institutions). The university provides cover for all sorts of anti-American, anti-capitalist activity under the disguise as education: post-colonial studies, radical feminism, Queer theory, Gender theory, Critical theory, Multiculturalism, Post Modernism, etc. This is all part of Cultural Marxism and it carries on today in the humanities and social sciences with professors hiring similar minded professors who have come up through the ranks as students.
3) Many of these professors are atheists and Social Justice or socialism is like a religion to them it provides them with a seemingly higher purpose and a feel good morality. To quote from Fr. Richard John Neuhaus, Socialism is the religion people get when they lose their religion. And this religious strain or higher purpose also contributes to a fervor that makes them to feel quite superior of the common man. It gives them, in great part, their smug elitist attitudes or the belief that they should be able to dictate to the masses for their own good. No wonder they wouldnt want to give that up.
To sum it up in a nutshell: human pride.
Was Thomas Sowell originally on the left?