Actually, vegans care about those insects too! The logic goes as follows:

• Plant-based diets not only don't kill and torture animals who have a higher capacity to suffer than insects, but just as importantly
• Plant-based diets use substantially fewer crops than animal-based ones. This is just a consequence of thermodynamics that every step of the chain loses more and more energy, and thus more crops are needed at each stage. This is a major reason (other than prions) why you won't usually see carnivores raised for food: it'd be wildly inefficient because you'd need way more crops and way more resource usage. The land usage for animal products is massive, and even the most "efficient" animals like chickens take 1.5 to 2 kg of crops for 1 kg of growth (we're talking about cows here, though, where the ratio is fucking enormous: around 4.5:1 to 7.5:1), and even then a lot of this growth goes toward things like bones which are used for byproducts rather than food.

Vegans don't eat insects because we care about insects. Vegans don't eat honey because we care about insects. And logically, we don't eat meat, milk, eggs, etc. because we care about insects. Veganism is about excluding animal exploitation "as far as is possible and practicable", not about being literally perfect. And the difference in scale here is enormous. This argument is made all the time without realizing that if you care about insects, the first and most effective thing you can do is not to use animal products.