Socrates is talking to Hippias of Elis, a travelling “sophist” who sets up as a professional “wise man”，taking money for lessons in private and public rhetoric, and managing public business himself. How, Socrates asks, does Hippias explain the fact that wise men in the old days were not rich public figures?
Socrates: Well, other skills have certainly improved, and by comparison with modern craftsmen the older ones are worthless. Are we to say that your skill — sophistry — has improved in the same way, and that the ancients who practiced wisdom were worthless compared to you?
Socrates: None of those early thinkers thought it right to demand money as payment, or to make displays of their own wisdom before all sorts of people. That’s how simple-minded they were; they didn’t notice how valuable money is. But each of the modem people you mention has made more money from his wisdom than any other craftsman from any skill. And Protagoras did it even before they did.
Socrates: What a fine thing to say, Hippias! It’s very indicative of your own wisdom, and of what a difference there is between people nowadays and the ancients.
Hippias thinks Socrates is complimenting him. The reader, however, sees clearly that Socrates despises the use of intellect to make money, rather than to search for the truth, and hence has complete contempt for Hippias. This is the “Socratic irony”.