Even when presidents are caught in lies, they often get away with it. Likewise, many presidential scandals lack traction at the voting booth.
Obama lied about Benghazi, but that didn't cost him reelection because it happened half a world away. The very name sounds foreign. So, for many voters, that's just an abstraction. They don't see the relevance to them.
Likewise, NSA snooping isn't overly intrusive. Not something you're normally aware of. So for many voters, out of sight–out of mind.
Likewise, the very fact that the IRS selectively targeted conservative groups means most voters don't pay attention.
By contrast, Obamacare is lie that sticks. It affects too many voters. It affects them drastically. And it affects Democrat voters as well as Republicans. So that's not something that Obama can talk his way out of by giving another speech or interview. Words won't make it go away. Tens of millions of cancelation notices go out.
It's more like a freeway pile-up that keeps getting worse. A chain-reaction.
You have the dysfunctional exchanges. That makes a very bad first impression.
In addition, if, due to the technical difficulties, only the most desperate individuals are prepared to log in the necessary hours to get through, that means the sickest, most expensive individuals are signing up first, which (so I've read) will spike premiums and deductibles for those who wait later to sign up.
Lack of security protocols will further alienate the electorate.
But in a way, the dysfunctional exchanges mask the deeper problems. When you successfully enroll, that's when the trouble begins in earnest. The system is lowballing enrollees on the actual cost. So they are in for a rule surprise when they find out what the premium and deductibles really amount to.
If that wasn't bad enough, not only are enrollees generally paying much more (they are frequently ineligible for the subsidies), but many doctors and hospitals are opting out of Obamacare. So you're paying more while losing access to the best doctors and hospitals.