Read up on marginal utility (which arises from subjective value) and you'll realize that once someone has a lot of something (e.g. bitcoin) they will want to trade it for other things - from things that meet their basic needs like food, to things that meet more advanced needs, like travel, entertainment etc. People don't want money, they want what money can buy.

Corn will trickle down on those offering goods and services bitcoiners value.

And you'll always be able to buy corn as long as you have something valuable to offer.