No, you don't get the money back. In theory you should act as if you got the tickets for free. You are going because you find the concert interesting, you do no

No, you don't get the money back. In theory you should act as if you got the tickets for free. You are going because you find the concert interesting, you do not go because you have already spend $50. Also you take into account future costs. If you want to go to the concert and there are several days that you can go, you choose to go to the one that you already have tickets. Attending any other day will cost you $50. Another cost is the social consequences. Maybe you do not want to go anymore, but you know that your mother will be pissed off after she gave you the money. Or you may be judged as irresponsible by your friends if you don't go. That you paid in the past do not matter anymore. But are there future consequences what you need to worry about.