The thing is, like arizen said, several species of bugs are going extinct. It doesn't matter how much they reproduce, as the world is still growing. Nobody is paying attention to those. We used to think we would never run out of oil, and look now. Everything comes to an end. Except for me, I live forever.
As I said, I'm sure there are people that do care. For every thing on this planet, there is at least one person that most likely cares about it.
But, again, you have to look at it from a larger perspective. There may be that one person that cares, but that one person isn't going to stop the whole human race from not caring. And why? Because no matter how special these bugs are to those people that care, if they don't do anything of interest to the rest of the population, they won't mind.
Let me reference my dragonfly example. If someone were to announce that dragonflies were becoming extinct, it would be very likely that a good number of people would care because, to most people, dragonflies aren't something to kill. They interest people, they don't bother people, they aren't extremely gross or unappealing. As far as most people are concerned, they are fine to do what they wish and don't present a problem.
So if they were brought under the endangered list, a lot of people would be worried by this or be a bit more cautious around them, even though humans rarely kill dragonflies purposely anyways.
Then, let's say mosquitoes were put under the endangered list. That would almost be a godsend to people. Mosquitoes are only annoyances to most of the population, so seeing them gone is nothing but beneficial. No more annoying bug bites, not having to worry about contracting diseases from them, etc.
My point is, humanity cares about things for odd reasons. If something appeals to humans in even one slight way, humans tend to care more. Do cats really do anything for humans? Not at all. But they are visually appealing and, now that they are domesticated (as they obviously were not at one point), can be great companions. But other than that, they don't really do much for us. Just for those reasons, we like them, so we prefer not to disregard them.
Evidently, most humans do not care for most bugs because if they do something, it's usually not something the human likes, whether it be being visually unattractive, harmful, annoying, noisy, etc. None of those traits appeal to the majority of humanity, so the majority of humanity does not care.
Also, continuing this, Arizen said:
"If I had a pet bug, I would be sad if it died. If billions of bugs died in a forest fire, I don’t know and don’t care. "
Very true. I would agree.
But, what if you watched the news and found that a thousand kittens died in that same forest fire? That would hit a nerve. Those aren't your kittens. They do nothing for you. But I would bet a lot of people, maybe even you, would have not wanted that to happen.
As humans, we give significance to whatever we want. We just never gave significance to bugs in general, save for a few, and even then that varies from person to person. I personally love bumblebees and enjoy their presence in my parents' garden in my front yard. Other people may hate them and try to kill them. Those are just those exceptions that happen in every topic.
But the point is, in general, bugs are not significant to humans, so you won't find that same care for them that we give to others. Not even cows.