Why do so many young girls go through a phase of being obsessed with ponies?

I did too and don't understand why. What is it about little girls that sucks them into the equestrian world and then, quite often when they realize that it is not all pretty colours, trotting around and plaiting then they leave? It's just that i'm now the only one in my family who has actually stuck with horse riding from a young age and I'm curious as to why this is as my cousins have all stopped now. They all also did not become anything more than novice riders while I'm quite experienced.