Entitlement.

That one word explains virtually everything you need to know about the left. They want government sponsored health care because they are entitled to it. They want you to shut up about it because nowhere in their personal sense of entitlement does it involve you having an opinion of your own or speaking it in any format. They are entitled to impose cap and trade on industry. They are entitled trade in their old car for a new one with a big government rebate. They are entitled to low taxes while voting for high taxes on people who are not them.

If you say anything negative, you are encroaching on their entitlements. That is why they become so angry.

As a good conservative, think about how you feel about freedom, access to the opportunity to work and vote and breath air. To understand liberals, you have to understand that they feel that same way about EVERYTHING.

They feel about health care the same way you feel about the right to vote.
They feel about the Prius the same way you feel about the right to own a gun.
If you tell them they can't get discounts for buying a Prius or they can't get free government health care, it's like someone going up to you and taking away your right to vote and own a gun. You would be outraged. Lefties are outraged like this all the time.

If liberals wrote the Constitution it would be 1042 pages long, filled with things that they have a right (not a privilege! a right!) to possess or control. And Item #1 would be the right to silence anyone who objects to their personal sense of entitlement.