I don't think it means that silence will necessarily benefit you materially -- rather that silence is something precious or valuable. Maybe consider the proverb's relation to these similar ones:
Still waters run deep.
Better to close one's mouth and be thought a fool, than open one's mouth and prove it.
The heart of the righteous ponders how to answer, but the mouth of the wicked pours out evil things.
The prudent keep their knowledge to themselves, but a fool's heart blurts out folly.
A wise old owl sat in an oak:
The more he heard, the less he spoke.
The less he spoke, the more he heard;
Why aren't we all like that wise old bird?
I'm a big rereader in general, but occasionally a book will grab me so hard that I finish it & begin again right away. I've had two of those in the past year: