First of all, no one knows for sure. But here are a few reasons at play:

Supply:

Roughly every 10 mins, 25 new BTC are issued ("block reward"). At ~$230 per BTC, that's ~$830K new BTC a day (25 x 6 x 24 x 230). As many miners sell most of the block reward to recoup the cost of mining, for bitcoin's price to remain constant, these new BTC have to be absorbed (=bought) by market participants.

Demand:

While the number of transactions are trending upwards (see Bitcoin Number of Transactions excluding Popular Addresses), it seems that there is not as much new interest in investing into bitcoin at the moment. Interest has stabilized, but may not be outstripping demand.

Risk:

In addition to the price risk from the fluctuating exchange rate, there is currently a very heated debate about the bitcoin 'software' with competing proposals on how to scale bitcoin in order to facilitate more transactions (BitcoinXT, BIP10x). Without going too much into detail, the discussion questions some of the core principles of bitcoin. (high-level overview: Brief thoughts on the Bitcoin block size debate)

So - do I believe Bitcoin will prevail? Absolutely. It will also probably make a great long term investment, but in the short term the price may even drop further. A few things may help a rising price:

More use cases, e.g., services utilizing BTC

Halving of the block reward to 12.5 BTC, due mid 2016 (Bitcoin Clock)

Settlement of the "scaling debate"

A rising price (this sounds funny, but a raising price itself will fuel additional demand).

Absence of catastrophic events (bugs in the code, network failure, etc.)

In the end, you need to be comfortable with your investments and the risk that you're taking. The fact that you're asking the question in the first place might imply that you're not :)