The big money's in forcing individuals to buy licenses to consume said food. Burpee first tried to do this with their hybrid seeds but because that was done the old way they weren't allowed to actually license it. However now that they do it genetically, they can. It's still unenforceable on the home garden end but half of all seeds produced by said crop revert back to the old less desired stock. In around 3 generations all you have left is the weedy part of the hybrid. Which is another scary thing about GMO's, they also revert back to their old, weedier, low energy stock.
SO... if any of you were wondering what was going on with the crops in the movie Interstellar... that was what it was. That little stock of corn was all that was left to clone. Put in another way and lets say it all together, that corn stalk was the last available specimen of corn plant left to G-M-O. Simply put corn and pretty much every other crop lost it's ability to reproduce because it's DNA was damaged beyond repair. The Blight explanation was just a lie.