If I say that iPhone has a use, that mens it is used as communicating device, music player, gaming console, camera, and so on. If I say that Dollar has a use, that mens it is used for fulfilling loan obligations - which is the reason it came into existence in the first place. Passing iPhone or Dollar from hand to hand is not usage but transfer. And transfer is performed via infrastructure that has nothing to do with iPhone or Dollar.
You're making up theories to support your claim. When USD was created its main purpose wasn't to provide loans to people but to work as a means of payment. Bitcoin can and is working this way, and being a payment service equals having a use. If we went by your theory paypal and others would not have a use.
If I make a bet and win iPhone or dollars this is also not usage, but transfer of an item from one person to another. Hence transferring, moving or gambling with bitcoin is not the usage of Bitcoin. So, I will ask again: how Bitcoin is used?
If you can gamble using BTC, it's fulfilling the role of casino chips. Do casino chips have a use? Of course they do.
If you win a casino chip, it is a transfer of value from one person to another, but the chip is fulfilling its purpose.