If everyone start storing bitcoin and there is no single transaction for days,all miners will quite mining as without transaction there would be no reward.
Will it not kill bitcoin and make it useless?
I dont see why storing bitcoin will kill it the reason for that is every individual sees bitcoin in different light and its use depends on what appeals to us in a different way, To some people, bitcoin is to be used as a medium of exchange and no one can change their mind about that while to others, they believe its to be used as a store of value those are the category of people that will keep their bitcoin hoping that it will reach $10000 when it does, they will wait till $100,000 so its going to be impossible for everyone to think and act in one same direction.