Why do we get punished after being good?

Reb נחמן מברסלב Used to say the following parable. There was once two friends one was Jewish, and one was a gentile. They did business together and ended up Erev Pesach together in a Jewish city. So the jew told the gentile to go to the shul tonight and someone will invite you over for a very lavish meal as the Jews are accustomed to invite a guest to there Pesach meal. So the gentile goes to the shul, and he gets summoned to some rich man's house. He is all excited about what he will be served and sits down to the table with the rest of the guest. He is waiting for the food to come, but he sees the host just praying and telling stories, so he starts losing his patience. After a few hours, he sees they are finally bringing in some food. He looks up, and he gets this hard cracker so he thinks maybe this is just an appetizer and then he finally sees them bringing in something white, so his hopes are lifted. As he was so hungry, he took a huge spoonful of this white thing not realizing that it was a sharp horseradish. As he made this huge bite, he felt like he was going to die. He got up in anger and left the house and runs to find his Jewish friend. He tells him the whole story and his Jewish friend tells him you are so stupid if you would only wait for the next course you would have gotten the sumptuous meal.