Last year’s superfecta paid only $63.41 - less than the trifecta ($202). There were fewer bets laid on the superfecta than the trifecta, and the bets that were laid were not randomly distributed.
http://helloracefans.com/pdfs/charts/2015-Kentucky-Derby.pdf
This year’s superfecta paid $542.10
http://helloracefans.com/pdfs/charts/2016-Kentucky-Derby.pdf
The 2014 Derby Superfecta paid over $15K.
A longshot finishing 2nd really drove up the odds.