"Chicago is not a "real" market for grain.  The cash market is the real market, that is where end users buy the grain that they need.  

By widening the basis they are telling you that they have enough grain and are not willing to pay what a suit in Chicago says corn is worth.

There is plenty of corn out there."

Basically it doesn't matter what Chicago "says" your grain should be worth, they (the funds) don't use it so they don't actually buy grain.

End users have plenty of grain available.

They aren't trying to "steal your grain" anymore than you were "trying to steal" their money in 2008.