Why?

Why would anyone cave in to the demands of a couple of little people hovering close to bankruptcy?
Because he fell for just one more trick.
The problem was that they could probably raise enough money to start an action. They wouldn't finish it.
But they would cause the savings of their victim to be absorbed. Thus ending any ambitions he may have had for his little bit of hard-earned money.
They probably thought they had nothing to lose, but some sort of 'gambling superiority' to prove, that illusion being more important to them than anything else, as it would provide the motive power to go on with their spree.

If only the Pinkys of this world were so visible,eh?