A poor milkman used to go from house to house every morning to sell milk. One day he had a big pitcher of milk, which he was going to earn a good income by selling. Carrying the pitcher of milk on his head, he was going towards the city when he got lost in thought.
He thought, "With the money I get from selling this milk, I will buy a chicken. The chicken will lay an egg every day. With that egg, I will raise a flock of chickens. By selling those chickens, I will get a cow. By selling the cow's milk, I will buy a gold necklace. Then I will have a lot of money. Then I will marry the daughter of the richest man in my village... and when we have a child..."
The milkman, lost in these thoughts, involuntarily waved his hands in excitement. The pitcher on his head fell and all the milk spilled on the ground. Now he had neither milk, nor pitcher, nor his dreams were going to come true.
Lesson: Getting lost in fantasies of what will happen in the future and not paying attention to what we are doing now is harmful. Excessive greed and unrealistic plans are enough to lose even your current wealth.