Speculators are not the cause of volatility, they provide liquidity and stable(r) prices. The fact that bitcoin has considerable volatility currently is not because of speculation, but because there isn't enough of it.
This may be true in whatever other markets exists currently that are connected to REAL WORLD supply and demand and companies... But bitcoin is an entirely new concept. It is NOT connected to anything else right now besides the speculating.
That makes it a gambling game and none of the posts so far have any basis in reality. There is no way you can say the speculator vs speculator trading right now is not the cause of the volatility. there is NOTHING else effecting its price.
IF somehow in the future there is alot of easy to buy things with set bitcoin prices (not fluctuating wildly based on its exchange rate) THEN and only then would you be able to say things like "speculation might not be the only driving factor in its volatility."