Because I haven't been there yet! 
There are many reasons which are valid to many other countries on the list.
Here are some: So I can practice Spanish, drink some nice wine, visit some lovely beaches, explore some ancient ruins and meet some interesting people. Another reason is that we joke in NZ that if you ever got lost on the sea (east coast) you'd end up in Chile.
Thanks for asking - I had to think some more about this.