I think it can be counter-productive, and can certainly lead to people buying in only to sell later as soon as they can. But I don't think this is the reason for price drops.

We have to consider how price is ultimately determined - supply and demand.

By definition, if a coin fails to hit hard cap then there is more supply than there is demand, so immediately you have that downwards pressure on price.

There is an added effect from 'bonus' buyers wanting to sell and the same from some bounty hunters, but ultimately lack of demand is why the price tanks every time.