Instead of a normal exchange where you can buy stocks directly, you pay the exchange 2.50$ per transaction and you would get a random stock out of thousand possible stocks and most of the time it would pay out a shitty worthless penny stock so the exchange makes money on the spread between the price of the 2.50$ fee and the penny stock paid out and the chance of getting a stock worth anything would be like 1% like a normal video game loot box.