I don't understand why or how they still exist. I know I'll get some answers saying they're part of the food chain but what animal on earth would get a sufficient meal from one of these?
What is the point of humans for that matter... And yes I am going to give you a food chain answer. You see, crane flies start off in the water as a larva. The larva is fat and plump and fairly large compared to the adult crane fly. While in larva state the crane fly larva is a sufficient food source for many aquatic creatures such as crayfish and other nymphs such as dragonfly nymphs. While in adult form the crane fly is consumed by many birds, while it may not be a sufficient meal itself, it is one less insect that the bird consume to be satisfied.
crane flies are very large. They might also play a part in pollination I'm not sure. I've never looked at the gawky insects before edit larave are decomposers in soil adults don't feed. So then the maggots are for the recycling of decayed matter. Thats their point. my info came from my field guide that is next to my bed at all times
Your question is one for philosophers or priests because it is a question about purpose. Scientists never ask the purpose of anything, they only ask about functions. There must be thousands of animals that eat crane flies: Fish, bats, birds, robber flies, spiders . . . the list is practically endless. I'm not sure I understand your question about how they exist. How does any living thing exist?