That's as much a straw man as Monsanto is to GMO. Just because some attempts failed doesn't mean it doesn't work.
And besides, that's not even the only way to control pests. Neither do we have to not use pesticides, anyway. That is just one example of how farming tech has improved.
Roundup is a herbicide. There some problems with it:
1. Some plant life has developed natural resistance to it so it's not going to last forever. At that point, the non-roundup supported ecosystem will be dead so there will suddenly be a fallout from using it.
2. The surfactant it's mixed with is toxic to humans and wildlife so you're going to kill everything with the run off and poison the water supplies all over the place.
It's a shitty solution to the problem.
GMO will feed idiots for a profit for a few years and kill the rest of us.
GMO will feed the world and I welcome them with open arms.