it seems a bit of a reach going from a reckless gambler (plunger) to a "simpleton".

Hermit, a 1,000-15 shot, nursing a serious injury, races from the back to the front to win the Derby. Epsom, 22 May 1867. Barely a week before the big race, Hermit pulled up with a broken blood vessel running in a trial at Newmarket. However, the rivalry between his owner, Henry Chaplin, and the Marquis of Hastings (who stood to lose £120,000 if Hermit won) ensured the colt's appearance in the classic. But with unseasonal snow flurries blowing across the Downs, Hermit's starting odds of 1,000-15 appeared a little miserly as he remained at the back of the field approaching Tattenham Corner. Suddenly he took off under the driving of jockey John Daley and at the winning post stretched out to beat the 10-1 chance Marksman by a neck. The Marquis of Hastings, it is said, went deathly pale.

http://www.findonvillage.com/0123_the_obsession.htm

this seems like extremely bad luck more than anything else (but proves once again that you should never bet the farm on a sure thing).

btw, I am unable to find a connection between Benzon and the Marquis.

http://home.mn.rr.com/wwftd/