Your life requires both the things you need to sustain it and the things you want to enjoy it. The truth is if you have not already at some point in time you were going to spend that money acquiring the things that you deem necessary or you were going to buy what it is that you want!
Think about money that you spend on the things that you want and need. You do so without hesitation and without the thought or concern of getting anything in return. Does it make sense to you to get up to 50% cash back on 100% of the purchases you make?