Why do those little flying insects swarm?

Those annoying little flying critters are back, especially around the waterfront where we live. They don't bite, but God are they annoying.

I've always called them "gnats", and that is a common name for them (although various species of gnats are really close cousins); others call them "lake flies". Technically, though, they are "non-biting midges" or chironomids, as opposed to biting midges (or "no-see-ums" in Canadian parlance). There are some thousand different species of them just in Canada alone, completely indistinguishable to us mere mortals.

But why do they have to swarm like that? Well, apparently,  the ones we see swarming are all males, and they hang out in clouds, often near water or around lights or other prominent objects, so that they are a more obvious target for females. Because pretty much all they do, and all they want to do, is mate. They literally are born, swarm, mate, and then die. They don't even eat. It all seems a bit pointless to me, quite frankly, although I'm sure they don't see it that way.