This could be anything an iPhone or idea..
For centuries, people are amazed at why someone is mad for something and finally call it his madness.
Whether it is Einstein's passion for science or Beethoven's love for music. And why to travel in the past, we can see the world's madness for a new iPhone.
I know many people may not agree with last one, but it is true. This is the feeling of the large number that there is something special in it. Though different people describe it differently, some call it its design and some says an extraordinary feeling of possessing it. And the rest of the world who do not agree with them they call it extravagant nature.
Analogy 1 : iPhone Lovers
Whenever there is the announcement of Apple's next product, all minds will start speculating the next big feature of the product. And the day when it will be launched, an overwhelmed response can be seen online and outside the Apple stores.
Many will oppose by saying there is nothing new in its incredible price, but only the true lover can understand its feeling. And this is what makes it special.
Analogy 2 : Parenting
For every parent their child is special. This is not only biologically related, but it is the process of promoting and supporting the physical, emotional, social, financial, and intellectual development of a child from infancy to adulthood. And this is also true that no one can describe this feeling. This is not that kid is special, but its parents' belief what makes him or her special.
Analogy 3 : Entrepreneur's idea
Similar to Apple's product lover dilemma, an entrepreneur cannot describe what's special about any idea. And this could be the reason to start working on your idea or the kick you have been waiting for. There is no secret about the success or there is no defined path to success, otherwise, one could easily follow and achieve what have been achieved by the Elon Musk or Einstein or Ratan Tata.
It is not the product or idea which is special it's all about emotion, belief and culture and may be more than that. In short, there is no secret ingredient, but it is the belief that something is special.