Transgenic BT crops hook farmer on GMO seeds.
Transgenic BT crops damage insect community structure in the field. While lowering the need for chemicals to be applied to control major insect pests, beneficial organisms on the GMO field are less stable than that of regular crop field. Iit is much easier for minor insect pests developing to be major pest. A farmer willing to grow non-BT non-GMO crops will have to wait 2-3 years before planting the desired crop to ensure that the return of the beneficial organisms. Since many farmers can not afford to keep the field idle for 2-3 years, once they switched to BT, they are hooked. (From NIH)