Mostly illusion. For starters, BT is an insecticide. For seconds, the numbers are suspect even without considering the looming resistance problem. The people who manufacture insecticide are not suffering for lack of sales - somebody's using the stuff. Third, most of the insecticide used was wasted anyway - industrially cheaper to broadcast than treat infestations, once the operations reach a certain size and type of organization - regardless of long term consequences. That kind of operation is abetted by GM technology. So the essential problem - indiscriminate and overkill broadcast of poison, with all the effects of such behavior including economic - remains. What the GM did was expedite the current broadcasting of insecticide operationally necessary in the newfangled industrial model agriculture - by deftly inducing the plants themselves to manufacture BT. The BT resistance inevitable in such employment will have the advantage of helping to kill off other, competitive models of agriculture, btw. A side benefit, for Monsanto and DeKalb and the like. Lots of plants and other sessile organisms manufacture insecticides, vermicides, fungicides, mammalicides, etc - that's why it's fairly hazardous to just eat plants: that stuff tends to be poisonous. We have had thousands of years of experience dealing with the normal plant poisons, and put hundreds of generations of effort into breeding them out of plants - which led to the problem of vulnerability in our domesticated crops - but we have little experience with this new kind of plant manufacturing of new kinds of poisons in genetically brand new ways. We'll find out, as always, by trial and error: let's not risk making the error too big, in the early going, eh? Wisdom counsels prudence.