The one goal of future contracts is for producers and consumers to be able to make deals before that production and consumption happens. Those are the primary dealers there, and I don't really remember where I got statistics, but AFAIK, they are about 10% of the volume.

On top of those primary deals, a lot of people pile up making bets on secondary deals. Those are the people going for "hey, a lot more farms are growing rice this year, I bet its price will fall". They are very welcome because they not only stabilize the prices on those markets, but they also provide short-term money to make the deals flow more homogeneously. Without them, making deals on those markets would be a profession by itself (as it was).

Now, there exist people making bets on the results of the bets of the secondary market. That is a different market. At some point it's clear that this becomes toxic, but nobody seems to agree on what point exactly.

> What about the crops they destroy because they would be less profitable?

You mean farmers getting bankrupt? You seem to be misunderstand, because the main reason farmers love the futures market is because it lowers their risks.

> How well will it work if we create unsustainable land that the farmers can no longer grow crops on?

Well, surely if you go and kill everybody, there will be nobody losing money on those markets.