You think having ads is unethical? It's not perfect but it is definitely not unethical. You are not being forced to use the app and you did not pay to use the app either. You have a choice to use the app, that developer does not have a choice when you stole from him. If you are hosting a chess tournament but you force the participants to not wear shoes inside, does that mean they have a right to cheat and get paid at the end? What absurd logic you are using! You stole from an independent developer, not some multi billion corporation like Walmart.