The practice of throwing a coin in a wishing well comes from Ancient European folklore. It is said the the elemental water spirits tend to make their homes at the bottom of wells. So tossing a coin to them, as an offering, would make them smile on you and encourage them to grant you a wish.
So much of our culture is based on this concept of making a sacrifice or offering of some sort, in the hope that the Gods or the spirits will look favourably on us.
I personally prefer to get off my arse and do stuff, to make my own luck. Far more reliable and productive than imaginary friends in the sky, or down the well for that matter. But then being half Irish and half Gypsy, my luck seems to do a pretty good job of looking after it's self. 😆