[zaarn]

It was hacked atleast once and the hacker assigned themselves a couple million coins.

Last time I worked out the numbers, Proof of Work runs about the same cost as the average US state's bureaucracy. All of it. And the US state's paperwar machinery does a lot more than bitcoin.

Centralized systems have much better options at running efficiently, decentralization is necessarily inefficient.

>They don't need to spend money on security, because mathematics is the security

Everyone working on quantum computers disagrees. The security of current wallets hinges on QC not existing since the ciphers aren't QC-secure.

And until we find something that is provably NP-complete in QC and normal computers while also being easy to use for cryptography, there will always be the hovering Damocles Blade of "your crypto has been cracked".