Comment by quantum_mcts

All your arguments has this implicit assumption of a central authority that you trust to do its job:

  - "SEPA is pan-European credit transfers". Emphasis in  "European". Good luck _reliably_ sending money to China or across Atlantic _in_several_days_. Reliable 10s is a dream there.
 
 - "Every country already has its native currency." Emphasis on "country". With a central bank that manages the supply. 

 - "All (democratic) countries have courts in place." Again, emphasis on "countries" and "democratic" (which you obviously felt the need to put in).

The fundamental technical innovation of cryptocurrencies is permissionless decentralized consensus - you don't need a trusted central authority to execute transfers and contracts. That is (in my opinion) where the fundamental "usefulness" of crypto stems from.