If a grown man believes in fairies, you would probably say that he has never outgrown his childish beliefs, but do children really believe in fairies? Well, I used to believe in the tooth fairy, but I gave up on her after I go my last threepence for my last baby tooth. (Santa Claus got a better run with me.) But, by and large, I viewed fairies the same as I did dragons (which used to give me the heebee-jeebies), witches, and talking animals: as "just stories", and I suspect that most children are the same.
On the other hand, many people would be surprised to learn that belief in fairies, elves, dwarfs, and the like has a long and venerable tradition in Europe. Like belief in witchcraft, it is one of the last relics of paganism. Indeed, one of the drawbacks of studying
genuine fairy folklore is that I can no longer tolerate the prettified, gossamer-winged monstrosities of children's books. The last stronghold of this tradition in Western Europe is
Iceland, where even some
politicians share the belief. There is even a government body dedicated to it. (This is not as stupid as it sounds. What do you do if citizens claim that problems with
road construction are caused by the elves?)
People may also be unaware that, when folklorists were researching fairy traditions in the British Isles during the 19th, and even 20th, century, they found people who not only believed in them, but also claimed to have seen them. Of course, they might have been making it up. Indeed, that is the only view you could take if you have already ruled out the existence of fairies. Now, I'm not saying that doesn't happen, but there is a certain fragility in any theory - such as the non-existence of something - which relies on the assumption that every piece of evidence to the contrary must be based on a lie.
Of course, the term, "fairy" carries a lot of baggage - magic powers, underground dwellings, time dilation, changelings, to name just a few - and it would be unwise to assume the whole tradition if you did happen to observe what something small and humanoid. So, I don't believe in fairies,
but ... there are still a lot of strange things being encountered. Like what happened in North Carolina in 1976.