It's not. VCs are investment professionals and are trying to avoid adverse selection just like everyone else. Here's a relevant quote from a recent Matt Levine newsletter:

> I think that, if you had only five minutes with a world-class trader, and you asked her “teach me the essentials of trading,” probably she would spend the five minutes on adverse selection. The essential lesson is that, if you are being offered a trade, that probably means it’s a bad trade; your job is to understand that thoroughly so you can figure out the exceptions.