Basically, the advantage of hot money is that there is more money, which can instantly raise the stock price and then drive retail investors into the market. Since the stock market is T+ 1, retail investors can only wait for the second trading day, and hot money can break out the next day, leaving countless retail investors to take over.

Futures is a T+0 transaction, and retail investors can sell it immediately without waiting for the profit on the second trading day, so the advantage of hot money becomes inferior (there are too many goods to sell).