Very expensive

My dad had this game on his phone and I loved playing it, so when I found this, naturally I was excited and bought it, only hesitating briefly over the price. You would think that an app that costs $4 wouldnt have any ads or FORCE YOU TO PAY MONEY TO UNLOCK LEVELS, but this one does, and its frustrating because I love the games, but I think Ive already spent $10 on this app. I will never again purchase an app thanks to this.

Why do they charge so much? about All-in-1 Logic GameBox, v1.19