This information is not completely correct, after the listing of the currency is announced, its price increases madly, but when you know that, the price will start to drop so if you want a guaranteed profit, use a bot to follow the news before the listing. After the currency is listed, buying it is a high risk risk.
Actually, this isn't the only outcome of the market, I did have interest in just trading newly listed coins on binance exchange for sometime and these are my findings. The outcome of a binance listing can turnout in three different ways. Firstly, since coins are usually announced hours before they're actually tradable on the platform, this gives room for manipulators to mess with the market by pumping the coins to outrageous highs that fomo will begin to come in and this might continue after it finally gets listed.
Secondly, nothing actually happens but this depends mostly on the market condition when this announcement was made. In bearish market, binance listing doesn't do much to a project immediately but there would be future benefits when everything returns to normally.
Thirdly, we have your scenario that involves the coins dumping as a result of early manipulations cashing out of their profit. Usually for a project with huge community backing and legitimate or hyped, they usually bounce back as the corrections doesn't stay long.