HEP! I NEED THIS GOOD ANSWER BY TUES. THE 11TH!---- wHY DOES bILLY'S GRANDFATHER SAY HE ACTED LIKE A FOOL WHEN HE MADE A BET WITH THE PRITCHARD BOYS?

Grandpa calls himself a fool for falling for the boys' trick and accepting their bet; he spotted Billy the money. After Rubin's accident and subsequent death, Grandpa feels responsible because if no bet had been made, things would not have happened the way they did, and Rubin would still be alive.