The websites crash.

Nobody expects all of the Obamacare websites to be fully functional on day one. And in theory that’s not such a big deal, given the long open enrollment period. But what if it’s November and the systems still aren’t working? Will people who get frustrated with the sites during their “beta launch” decide not to come back? What if the errors aren’t immediately visible—and people get incorrect information about subsidies initially, only to learn later that they are entitled to less or more money than they thought?

Fear factor: 7 (out of 10)

Don’t worry: Big IT projects always have a lot of glitches. Just ask the kids who bought SimCity and had to wait weeks before it worked properly.

Worry: Those kids playing SimCity didn’t need health insurance. The people waiting for Obamacare do.

If things go badly, don’t be surprised if…: The Department of Health and Human Services fires some government contractors—i.e., the ones buliding their websites—and hires a bunch of people to read paper applications.