Quinn was 12 when this all started. Having grown up in a world with a dwindling number of aircraft you can imagine he hasn't flown much - but he seems perfectly calm and composed riding wing on a helicopter.
Sure, with the male dragon dead, the species won't be able to create any more offspringnote Although see below, that might not be the case if dragons can gender-swap, but who knows how long the lifespan of all the remaining dragons will be, including eggs fertilized but not yet hatched? And since dragons can fly, each survivor could hunt a very large territory once the competition thins out.
Since it's females that lay eggs and thus increase the fecundity of the population, the idea of one male and many females actually better justifies their rapid reproduction, as opposed to one female Hive Queen and many males, as then there would only be one individual reproducing (assuming she didn't have the reproductive rate of a queen termite, and even then would be limited by a single egg layer.)
Having only one male in a species is kinda stupid - it's an obvious vulnerability. Except that's a perfect representation of how evolution actually works. Evolution doesn't plan for future threats - it just sticks with what's working until it doesn't. One male worked brilliantly for those millions of years when there was nothing around that could seriously threaten it. But as often happens, the world changed and the evolutionary strategy that had served well under different circumstances failed, resulting in extinction.
They could've done a Sequel Hook with it too, maybe unfertilized eggs could've been what causes male dragons, hence the Alpha dragon made sure to fertilize all eggs and the smaller dragons we see him eat? his sons; btw the male unfertilized thing is an actual thing it's called Haplodiploidy.
We also don't know that the species as a whole has always had one male. The dragons we meet are the survivors of the original famine that ensued after they wiped out the dinosaurs. It could be this is the only colony that made it to the modern era.
From the Artistic License – Biology page: A whole species consisting of thousands of females and only one male? It's actually not impossible in real life: Blue-Headed Wrasses (a fish) have a reproductive pattern where they live in large schools of females led by a single male. When the male dies, one of the females actually switches sex and becomes the new male. In the film, though, killing the male results in the extinction of the species — the biological version of No Plans, No Prototype, No Backup — which is why it's listed here.
Which makes for Fridge Horror if it turns out the species isn't going extinct after all, they're just going to have to wait for a female to finish switching over to male and then it can start all over again....
During the opening it is a young Quinn who first encounters the male after it wakes up from hibernation, then during the Final Battle after Van Zan is killed and Alex is injured it is Quinn who manages to slay the male using the explosive crossbow bolts, which makes him both the first and last human the male dragon lays eyes on.
