He simply had to say to anyone close to him:
“I know everything.”
And that will reward him with money!
The kid first went to his father, he approach him and said “Dad, I know everything.” His dad’s eyes widened and quickly gave him 100$ and said “Shh. Don’t tell anyone please.”.
The kid then went to his mother across the room, excited, and told her “Mom, I know everything!”. His mom was shocked and her jaw dropped, she gave him 500$ dollars and begged him not to tell anyone as he was walking away with joy.
The mail man came knocking on the door, and was greeted by the same kid, the mail man handed him the mail, but out of nowhere the kid said to him: “Mr. Mail man, I know everything.”. The mail man suddenly teared up in surprise, he got on his knees and said:
“Come hug your daddy!”