Franklin always promoted saving and being frugal. Those who spend lavishly (fools) often invite people to enjoy in it and it's free to those who would normally be frugal. Thus, wise men partake.
^^ My interpretation.
It could also be a commentary on class structure as the uneducated would do the manual labor of preparing the feast and the successful, educated folk would be the ones to eat it, but as this is Franklin, I highly doubt that this is the case.