There's a lot of money in the low-end of the market, especially in the near future. Over the next decade or so the developing world is going to add on trillions of dollars in GDP. That's going to bring a lot of people to the table who will be able to afford a low-end smartphone or tablet, and for many of those people it will be their first computing device. Due to sheer volume alone there is a ton of money in that market. And that's in addition to the low-end of the market in existing developed countries, which is already huge.

However, the 5c isn't in that market. It's a $550 phone. It's only seemingly "cheap" because the usurious financing that most cell companies use enables them to offer a low down payment amount.

Look at it in two ways. When you lock yourself into a 2 year contract you're going to be paying about $1k for whatever device you upgrade to. The difference between $100 and $200 up front is trivial in comparison to this. So paying $1100 for a $550 phone versus $1200 for a $650 phone is, well, stupid. Even more so when you consider the performance and quality differences between the 5c and 5s.

That's at the high-end, for people who can afford expensive plans and expensive phones. At the low-end the 5c isn't competitive either. If you comparison shop un-subsidized phones on prepaid services you see that you can get LTE android devices in the $200 to $300 range, a Galaxy S3 is only $350. With an S3 and a $35/mo plan (virgin mobile) someone will be saving a minimum of $500 and closer to $1000, for comparable service, over 2 years compared to buying a subsidized 5c from verizon or AT&T. Even more if they opt for a truly low-cost phone (which can be as cheap as $150 unsubsidized for LTE capable devices, and essentially free if you don't care about LTE).

So it doesn't compete on the low-end because it's too expensive and it doesn't compete on the high-end (where its price puts it) because it's missing stuff.

No wonder no one is buying it.