For we have spent enough of our past time doing the desire of the Gentiles, and having walked in lewdness, lusts, drunken binges, orgies, carousings, and abominable idolatries.
The primary thought here is that through their own experience those Christians who had forsaken Gentile debaucheries to obey the gospel already knew the frustration and emptiness of such a life.  Peter's words here imply, "Surely you have already had enough of such things."  We found Paul making exactly the same appeal, "What fruit then had ye at that time in the things whereof ye are now ashamed? for at the end of those things is death"  (Romans 6:21).