Notice how nobody ever talks about using bitcoin to buy drugs or whatever anymore like they used to, that's because the black market aspect (one of the factors driving demand early on) has moved onto other more efficient and discrete coins. This coupled with the fact that the transaction costs are high means that it's not worth using for any small purchases. And further, the volatility of the coin makes it further shit for using as a currency, you sell something for 2 bitcoins today and find out tomorrow that you've lost $20,000 because bitcoin had a another bear moment.
The volatility, transaction fees and superior alternative coins all make it a shit currency. Why then is it retaining its value? Because people are speculating on it and using it as a storage of value, it's all dependent on bitcoin consistently growing and recovering from its crashes. It's a giant pyramid scheme at this point and the longer it goes on, the more bagholders there will be. It's one that's been strangely immune to popping because the recovery from previous crashes has been followed by a boom, which means there's a horde of people just waiting for the dip to sink a whole lot of money in.
Bitcoin will be stable for a while, lots of financial institutions are now hedging their money in there because the stock market itself is volatile in its own way. It's a safe bet at the moment due to the aforementioned fellas waiting to buy the dip, but once the economy recovers and bitcoin stops its bull run, you'll see that money start to seep out.