Imagine betting, but without a bookmaker. You trade directly with other people, and you can sell before the event ends.
You choose YES or NO and the price you are willing to pay. Another trader takes the other side at a price you both accept. BrainJuice matches the trade; it does not bet against you.
You offer to buy YES at $0.40 per share. Another trader accepts the other side. The trade is made at the price you both agreed on.
After the trade, your shares stay tradable and their price can move. You do not have to wait for the result: you can sell at the current price. If the price rose, you can take a profit early. If it fell, selling means a loss.
Profit before fees: $7.00 − $4.00 = $3.00
You sold before the event happened. If you do not sell, you keep the shares and wait for the result.