I think they both work hand in hand, it is the purpose that bring about the value, without the purpose, there is no value, the price of bitcoin is as important as its purpose, so also is the purpose as important as its price.
Think of it this way ... If bitcoin was not useful --Purpose
No body would value it --price
And if price was not high as to draw the attention of many, alot of persons on the other hand would never discover bitcoin , let alone knowing it purpose ..
So both price and purpose of bitcoin work together for the good of bitcoin.