Imagine a special gumball machine that gives out toys. Some toys are common (not worth much), and some are super rare and valuable. Normally, when you put in a coin, you're supposed to get a random toy - maybe common, maybe rare if you're lucky.
But I discovered something amazing! This gumball machine isn't really random at all. It decides which toy to give you based on a secret pattern. I built special glasses that can see which toy is about to come out before I put in my coin.
At first, my trick worked like this: I'd peek through my special glasses, and if I saw a boring toy coming next, I wouldn't put in my coin. I'd only spend my money when I saw a super cool rare toy was next.