In the recent time, the price of ICO tokens are often dumped deep after listing. There are many reasons for that result. The first reason, the current market is very bad. The number of participants in cryptocurrency has dropped sharply. The second reason, the team's strategy is not good. Many teams seem to abandon the token's price after listing exchange, leaving the investors behind.
Now this problem comes from the fault of the investors themselves because they do not believe in the project. And those who participate in the pre-ico stage - sell their tokens after listing on the exchanges
I think not only the investors who dump token after listing some other bounty hunter also dump tokens, but we cannot blame them about thier decision if they think that was the right thing to do. I believe that the solution is on the developer maybe they need to lock the tokens so that no one can sell it emediately.