this is normal for projects with weak background. Bounty hunters dump the tokens because they didn't pay anything, plus pre-ico token owners payed only part of the price, so first investors on exchange cannot do anything with this
Majority of the tokens are not great projects too and they will eventually die off, if the project is solid the price will increase in the future, even if the bounty hunters sell off the coins and we usually see the price going down when it enters the exchange, but there is a sell off from the team too, it all depends upon how good the team behind the project .