You can turn anything into your purpose. The reason why nothing prevents you from doing this is because purpose is not handed down to you by God or the universe. there is no destiny.

What if we let go of this one big ultimate end and stick to what seems to be true, which is that there are multiple mental states that feel good. In fact, no two mental states are alike because they happen in time and what happens in time does not repeat. So, perhaps, the measuring stick is not that one big concept but this: What feels good? The purpose is to feel good. Feeling good is an all encompassing lable to describe various never-repeating although similar mental states that are rewarding enough.