Bitcoin is virtual currency.
bitcoin is not virtual, it is pretty real. please stop using that word for bitcoin.
this topic has some good arguments against these types of words being used to describe bitcoin, I suggest giving it a read:
https://bitcointalk.org/index.php?topic=1733918.0unil now bitcoin nothing real physic
The money you are using isn't physical either. Just because you are using coins and paper does not mean anything. A currency is whatever two parties agree a currency for a trade is. No matter if it's fiat, cigarettes, Bitcoin, stones. If just enough people agree to accept something as a valid currency it's a currency.
and physic bitcoin only collection can't use transaction
See above
Just as long as not enough people agree to accept this collection. If they do, guess what, it's their currency.
//alex