Speculation would cause reaction to many investors depending on what the speculation is, but that's not the primary factor in affecting the price.
Once the investor reacts, it is either selling or buying.
That's why when there are many reactions to a lower price, investors tend to take chance of buying those dumped coins.
Increasing demand while shortening the supply. That's what affects the price.
Most traders lose money and it's down to this fact, that people in there, retail ones anyway, all react when they know they're not supposed to. It even happens to big funds too since they rely mainly on individuals to broker their trades on the floor. Panic, reactions, regret, fear, bad decisions.
Buying the socalled dip isn't a great strategy for shitcoins either. Trust me, I learned this the hard way!