As Courtney says - I think maybe you have some decimal place errors here!
I would say your message related to the Week 41 Free Multiround at Bethpage - where you finished T20th in the Legend Tier. The numbers look about right for 17.77 credits.
The total prize pool for Champion was 4,000 credits --- could this be where you thought you saw 40,000 ???
You tied with 18 other players for 20th --- so if you add up the prize winnings from 20th down to 37th it is around 14.2%
Your Legend prize pool was 2,250 credits -- so your share was close enough to 17.77 credits.