Contrary to how they view other federal programs, departments, and agencies, they inevitably place Social Security in a sacred category, one in which this particular federal program, they say, needs to be saved, reformed, fixed, improved, or gradually phased out over the next 50 years.

Consider, for example, the Federal Reserve. Many years ago, Ron Paul struck a surprising chord within a large segment of the populace by calling for an end to this federal agency. Paul's  mantra "End the Fed" became extremely popular all across the political spectrum and with people from all walks of life, including libertarians.  

Consequently, "End the Fed" has become a popular — almost trite — mantra for most libertarians. It is difficult to find libertarians who say that the Fed instead should be reformed, fixed, improved, or gradually phased out over the next 50 years. Almost every libertarian answers "End the Fed" when asked for his position on monetary policy.

It's pretty much the same with respect to the war on drugs. While some libertarians call for drug legalization for only marijuana, I think it's safe to say that most libertarians favor drug legalization for all drugs. One will not find many libertarians saying that drug laws should be phased out over the next 50 years. The position of most libertarians is abolish drug laws immediately.

Or consider the federal Department of Education. I think it's safe to say that most libertarians would say: Abolish it now. 

Yet, not so with Social Security. Why the difference?

I think there are two major reasons: 

First, there is a common perception that people have put their money into the system and, therefore, have a right to get it back. 

But that is clearly not the case. Social Security has never been a program in which people have had their money taken from them and placed in a retirement account. Social Security has always been a plain welfare program, no different from food stamps, public housing, and welfare. People are taxed to fund welfare-state programs but their tax money is not saved for them until retirement. It is spent as soon as the government receives it.