Currency debasement is the act of lowering the intrinsic value of money, e.g lowering the gold content of a coin.

Since the intrinsic value of a bunch of numbers on a computer is 0, this is technically true, but only cause it can't go any lower.

> - arbitrary seizures

It also prevents non-arbitrary seizures as part of legitimate law enforcement action. Child porn rings, organized crime, etc etc

Sure, you can keep it under your bed and assume all the risk yourself and not earn interest; that was OK while it was an appreciating asset, but that's not something you can rely on.

- changing or rotating those keys (basic infosec)