20 years is the max length of nearly all patents. So you really aren't giving them any concession there.

Also, all patents are monopoly. That is actually what a patent provides, it provides a limited government sanctioned monopoly over the invention.

> all patents are monopoly

Come on. Every product is then a monopoly because it’s the only one of its kind.

If your GMO seed plants 80% of its crop in the country, no patent. Otherwise, farmers choosing to plant your seeds are making a choice and should pay.