1. Bugs are not scalable.
There is no way to make bugs a suitable replacement for existing protein sources, specifically meat, fish, eggs, and poultry. The amount of bugs you would need to feed even a single large city go well past anything resembling sustainability, and would result in sweeping malnutrition under the best of circumstances. This is on top of numerous existing shortcomings involved with switching to bugs, including widespread allergies, the fact that numerous religions cannot eat them at all under scripture, and the simple fact that it would require massive, sweeping changes to pretty much every sector of the economy food-wise to make happen. Bugs are simply a less viable product cost-effectiveness wise, and never will be more cost-effective than their alternatives: they have a really low survival rate under the best of circumstances, because they're fucking bugs. Crickets, under ideal settings, have an over 45% mortality rate. The most efficient known bug raised, Argentinian Cockroaches (which are raised as feeder insects), have about a 75% rate. For every three roaches that are harvestable, one never makes it that far.
2. Bugs are less efficient and just as polluting as conventional meat.
Most bugs for consumption are fed a diet of dry cereals, fruit, and vegetables - in other words, things that humans can eat. Multiple studies on industrial farming for mealworms has shown that they have repeatedly failed to match poultry for efficiency, and when fed diets of grain by-products, straw, and so on, they frequently died before reaching a harvestable size - in other words, you cannot simply feed the bugs crap and expect the bugs to be harvestable for food; you have to feed them good food to get any result. Moreover, insects are ectothermic, which means they need to be kept in climate-controlled environments, or they fucking die. That means heating and cooling elements running all day and night. Under the best of circumstances, the FCR for insects is still only on-par with Chickens, which can be raised literally everywhere (there is not a single county in the United States that does not raise them), which means that even if the bugs themselves are less-impactful environmentally than the chickens in the short term, everything done to make the fucking bugs edible is an order of magnitude worse.