how do people find out about the listing of new coins even before the official announcement? I constantly learn about the listing of a particular coin from traders, and not from official statements.
That because there are early spots for some what we called private sale/seed sale or presale. These people invested earlier even an official announcement from an exchange happened.
This is also privilege if the project they are invested is good or high caliber. But if the project is not good, then they are also at risk losing such money if the price tank during listing.
Info can be get to some prominent channels and groups. If you are affiliated to right people then finding these aren't hard.