The reason we aren't all dead is that humans exist atop a mostly separate food chain from wild animals. If all wild insects die, there will be collapse of wild ecosystems, but crop yields will be the same, if not better due to the lack of pests. Most pollination of commercial scale crops which need active pollination is done with rented beehives, these days. See https://en.wikipedia.org/wiki/Pollination_management
[Epistemic status: high confidence grounded in empirical observables, no domain expertise]
In fact, those shockwaves up the trophic chain are already being observed: https://www.theguardian.com/world/2018/mar/21/catastrophe-as-frances-bird-population-collapses-due-to-pesticides
The reason we aren't all dead is that humans exist atop a mostly separate food chain from wild animals. If all wild insects die, there will be collapse of wild ecosystems, but crop yields will be the same, if not better due to the lack of pests. Most pollination of commercial scale crops which need active pollination is done with rented beehives, these days. See https://en.wikipedia.org/wiki/Pollination_management