Why does Henry get into a shouting match with his wife at the horse auction?

When Henry arrives at the horse auction, he has a mere five dollars to his name and inexplicably bids it all on a wild horse. His wife is shocked that he would be so frivolous with their money and begs Hipps not to take the bid seriously. Henry is outraged to be second-guessed by his wife in public and shouts for everyone to ignore her pleas to have their money returned?