This is a typical scenario for the new coin after listing, people who worked for that coin would like to sell it right away to for a quick cash or they know that it would dump, so basically sell high then buy low. Depending on their targeted income, some just sell it right away and would rather add it to the coins in their portfolio.
Most of the time, early investors dumped the coin after recieving it and see the asset was listed to an exchange, knowing that they'll already gain well enough to release the coins.
Very common and it's part of the cycle, the early birds catches the worm as they say. It's been applied and those who are good in finding new projects to ride along, they are gainers and they just keep repeating the process for the best benefits to have.