Italy is a fairly a new country (it was born in 1861) and before that each part used to speak a different language which, just like Neapolitan, they are still alive. These languages and dialects are not taught in school so the only way to learn them is by listening to those who passed it on which I think it's pretty cool.
In my day-to-day life I speak a mix of Italian and Neapolitan (but there are people who speak only the latter) but we try to use only the former when we speak to people from other parts of the country who wouldn't be able to understand us. Nowadays our local language is getting "italianized" a bit but it's still different from it, just like Spanish and Italian or other Romance languages.
Thank you for giving me the opportunity to let Lemmers know about it :)