nobody was born to be good with their fingers.
you think those child prodigies only practise the piano an hour a
week? 
but think of the cost.. if you learn the piano, you should own a
piano as well, which can cost at least about $3000 for a good
second hand one... or $1000+ for a lower-grade second hand
piano...
a guitar only costs about $100+ (I think) if you only want
something you can play with...