Yeah it's not like there are mechanisms to deal with this sort of volatility (hint - futures).
It is also a technique mostly for businesses, not consumers. How many consumers do you hear about controlling next month's food bill by buying their produce on a future's market? Right, none.
This ignores a subtlety. If one consumer locks in a large fraction of the supply at a low price, then the supply is smaller than expected, you've made the supply-demand problem more extreme for everyone else. So futures allow entities to lessen their own volatility, but that increases everyone else's volatility.