It's interesting to know why the volatility of the crypto currency will decrease if capitalization and the market increase significantly 
I believe that, despite the unstable price of crypto currency, we will still use crypto-currencies more often, as a means of payment.
If there are many investors around the globe and and the price of bitcoin increases, the level of manipulation in price would be really low because you cannot purchase and hoard or manipulate huge number of coins when the price is high, still the whales who are holding the coins could sell off their coins and manipulate the market as we see now with the Mt Gox liquidation, they are selling off their coins in huge numbers that are affecting the market.I believe that, despite the unstable price of crypto currency, we will still use crypto-currencies more often, as a means of payment.