Why did I bother to restart playing Candy Crush Soda?

I play games for fun - as stress relief.  I don't mind challenging levels  however some of the levels are so aggravating and frustrating that they add to my  stress instead of relieving it.  I was one of the earliest players of Candy Crush Soda but had stopped playing when the levels became ridiculously difficult and NOT fun.  Recently you sent me a nice message asking me to 'Come Back'.  Well I came back and now  wonder why on earth I did that.  Why do you make levels - for example level 315 so FRUSTRATING???????