Everyone has heard that where a rainbow touches the ground you will find buried treasure. Not many people believe this any more, and science suggests there is no such spot anyway - where a rainbow appears to touch the ground is completely dependent on where you are standing. Leprechauns don't dispute this but say it is missing the point. Which is that in chasing rainbows what matters as much as anything is knowing when you are in the right spot from which to view the rainbow. It depends as much on knowing where you are coming from as where you are going, which requires a particular kind of instinct.
Not many humans have it, so for most of us chasing rainbows is a pretty pointless occupation; but leprechauns, being that much more in tune with the hidden currents of destiny and time and all that kind of thing, are quite often successful.