It is not famous people, it is Hillary Clinton. As the article says, famous people get paid less than 50.000. Why does Hillary gets paid five times that amount: 1-Because the Clintons already repealed Glass–Steagall Act removing controls on the financial industry and giving them billions in the process. Even a million is nothing compared to the billions they have received and the billions they will receive from Clint…
Scott Adams, the Dilbert cartoonist, has openly written about being paid well over 100k per speech, several times a year. You can Google this. George W. Bush charges, on average, 150k per speech. A-List and B-List celebrities can easily get well in the six, occasionally in the seven figures for a public appearance of this sort. Rutgers University even paid Snooki about 32k for a commencement speech, if you remember this delightfully controversial event.
You have to keep in mind that for such events, the speaker usually does not constitute the majority of expenses. Organizing meals, booking a venue, and other logistics are not cheap already. Above all, such events are mostly for purposes of showing off or building morale: organizers want attendants (usually employees) to feel good about where they work. Just like with other kinds of corporate-level showing off, there's a big budget.
If anything, I think Hillary Clinton is paid surprisingly little for her public appearances (even though they do happen in great quantity).