The Gemara in Megillah 7b says
מיחייב איניש לבסומי בפוריא עד דלא ידע בין ארור המן לברוך מרדכי
A person is obligated to besumi on Purim until he doesn't know the difference between the cursedness of Haman and the blessedness of Mordechai.
Now, the word besumi is an unusual word, but luckily Rashi is there to tell us what it means:
To make money with wine
So we have to make money with wine on Purim.
This was easy enough for Rashi, since he had a vineyard and was a wine merchant. But how are you and I, the common Jew, supposed to profit from wine on Purim?