Bitcoin is very useful in the world and it is not available in the paper form but it is virtual currency and we can use it through this way crypto currencies are existed in this form but if this available in the paper form then people will keep it with them at home and we will not aware of the supply of crypto so if this is in the virtual it is good and bitcoin can never be eliminated from the world once it is started then no one can stop it but some times are very hard for crypto users when market is in chronic stage.