Actually its really have an affect to the pump and dump of the market if new investors are lessen or adding because we all know that crypto currency is a decentralized platform of investment the more investors the higher the price of the market because the demand will increase but it not just only by the new investors but to the old investors that really support crypto currency to invest.
I think If a small investor dominates the market, you will see less volatility and for now we need more pumping than dumping.
What is the price of fluctuating bitcoin is the volume and you can understand this from the order book when big buyers buy into the market you will see prices fluctuate and when they throw them hold you will also see prices getting dumped at alarm level.