Right now, thousands of people are betting real money on whether it will rain in Tokyo tomorrow. On who wins the next election. On whether a startup will ship on time.

The weird part? They're usually right.

This is a prediction market. And before I explain how it works, I want you to experience one.

See what just happened? Those dots weren't random. They followed the probability. Run it again. And again.

That price you saw? That WAS the probability.

When a prediction market shows "$0.65", your brain wants to think "sixty-five cents." But what it actually means is "65% chance this happens."

The price IS the prediction. That's the whole trick.

Here's the elegant part. Every prediction market is secretly about one thing: a dollar.

There are two outcomes: YES and NO. One of them WILL happen. Whoever holds the winning side gets $1. The loser gets nothing.

Try it. Tear the dollar yourself:

Notice something? YES + NO always equals $1.00. Always. This isn't a rule someone made up. It's math.

If YES costs 70¢, NO must cost 30¢. If you bought both, you'd spend $1 to guarantee winning... $1. No profit, no loss. Perfect balance.

This is different from a casino. There's no house edge. No vig. Just you and other traders, splitting a dollar based on what you each believe.

Here's where it gets interesting.

The market says 40%. But you've been following this story. You've seen data nobody else is looking at. You think it's actually 60%.

That gap—the difference between what the market believes and what you believe—is called your edge.

Edge is where profit lives. But here's the catch: you might be wrong.

The slider above isn't just a calculator. It's a mirror.

Every time you think "the market is wrong," you're claiming to know something thousands of other people don't. Sometimes you're right. Often you're not.

The trap: It feels good to disagree with the crowd. But feeling confident and being right are two very different things.

Time for a test.

I'm going to show you some bets. Each one has a price and a "true" probability (pretend you have perfect information). Your job: decide whether to bet or pass.

Don't overthink it. Go with your gut first.

How did you do? If you took all the positive EV bets and passed on the negative ones, you've got good instincts.

But here's what the game doesn't show you: in real life, you don't know the true probability. You only have your estimate. And your estimate has error bars.

This is the part most people skip. It's also the part that matters most.

Finding edge is only half the battle. How much you bet matters more than what you bet on.

Watch what happens when five traders with the SAME edge use different bet sizes:

Run it a few times. Notice anything?

The aggressive bettors sometimes win big. But they also blow up. Often. The conservative bettors are boring, but they're still in the game.

The Kelly Criterion is a formula that tells you the optimal bet size. Most pros use half-Kelly or less. Why? Because survival beats optimization.

A 20% edge with 5% position sizes will beat a 30% edge with all-in bets. Every time. Given enough bets.

Some traders are consistently right. They have better models, faster information, or deeper expertise in specific domains.

We call them whales. And we track them.

Not to copy blindly—that's a fast way to lose money. But to understand: what are they seeing? Where are they looking? What do their moves tell us about the market?

When a legendary trader suddenly takes a large position, it's a signal. Not a guarantee—but information. The market often moves after whales move.

The question isn't "should I follow them?" It's "what do they know that I should investigate?"

You've learned the core concepts. Now it's time to play.

Below is the full toolkit: calculators for EV, position sizing, odds conversion, hedging, and more. These are the same tools we use to analyze whale trades.

Experiment. Break things. Ask "what if?" That's how you develop intuition.