Because the idiots in this country can't seem to NOT go to the ER every time they get a sniffle. Add the panic of this virus they're reading on Facebook and hearing in the media and they'll all be rushing to the ER at the first sign of a cough thinking they have days to live, when in reality, the vast majority of them will be just fine and the limited resources we have need to deal with the people who won't be fine.
OR.... because our healthcare system isn't as good as everyone says it is. How many % of GDP is our pile of shit healthcare again? And it can't handle a simple flu? It's good at taking people's money. That's about it.