I remember seeing the founder of a crypto project publicly boast that the project had recently earned tens of millions of US dollars in transaction fees. I was a bit suspicious. This project hadn't even issued its own token, and it didn't seem to have any special features; I didn't think anyone would use it. How could it earn so much in transaction fees? Upon closer inspection, it turned out they had found a big-name investor to endorse it, attracting many people to try and profit from the arbitrage. These people contributed transaction fees, which were deliberately set quite high. In the end, sure enough, they all lost money.