Also, no bitcoin is not musical chair. It's the complete opposite. The bitcoin in my wallet is mine. I have a guaranteed chair.
Let's say BTC is completly mined. No more is created and you have your BTC in the wallet and follow through with the idea that it is currency.. Because it's a set number of units the price only goes up so you have little incentive to spend it. Saving it will result in a higher and higher value per coin. I don't see how you can have BOTH decentralized "currency" and a store of value. Your previous argument that said "What other currencies can do XYZ" is a false argument because you're listing all the things you like about bitcoin. One could do the same for USD and then ask, "How could BTC ever do all of this!!!"
It's like housing in a good neighborhood. You can't have both affordable housing and a continuous rise in prices. The two are in direct competition with one another.