GOLDMAN SACHS did not purchase Poloniex or have anything to do with it. A company they have a vested interest in called Circle is who made the acquisition.
Circle is a financial institution that specializes in peer-to-peer transactions similar to Venmo in the US. Circle raised millions of dollars from not only Goldman Sachs, but many other investors. Circle originally had plans that revolved primarily around Bitcoin but changed their focus and have now acquired an exchange.
If you’d like more info then DYOR, but please stop falling for clickbait and spreading fake news…