Please don't be disheartened by this cretin. I've honestly never seen anyone behave so entitled towards someone who spent hours, days, weeks and probably months creating something for others' pleasure. It's probably just some kid who is used to writing crappy reviews for freemium games on the App Store, and who has never done anything nice for anyone in their lives.
Your work is greatly appreciated by so many people, so please keep it up! 😊