The flow of a currency is crucial to its existence. If no one would spend bitcoin, it would not take long until its eventual death.
most of the transactions right now are related to buying and selling btc. if btc was on the brink of death people would start selling there btc and this would increase transactions.
but also this might create a run and price collapse.
Have some of you thought of that when Bitfinex is told that it is hacked? I think that the real reason that price went down that moment is because people got scared and sold some of their coins, I think even just ROI is sufficient and they left some in case it will be still alive.
Selling will really collapse it. It is different than making using it through buying something.