Here's why:

* Numbers: There are estimated to be over 900,000 known species of insects, and potentially millions more yet to be discovered.

* Diversity: Insects are incredibly diverse, encompassing everything from tiny ants to giant beetles. They inhabit almost every environment on Earth.

* Other Arthropod Groups: Other major arthropod groups like crustaceans, arachnids, and myriapods, have significantly fewer species compared to insects.

So, while the other arthropod groups are fascinating and important, insects reign supreme in terms of sheer numbers and diversity.