The silly thing is that your "blockchain" could be the smartest thing in the world, have super incredible cryptography or whatever. You can have the smartest developers in the world writing the software without bugs.
But you run that software on a mainstream operating system (Linux/Windows), your funds are not safu - they're just one confused deputy away from being stolen.
Having a secure by design operating system is a fundamental requirement for "blockchain" to ever become more than an online casino.
Online payments through centralized entities don't have this problem. If you get hacked, someone can revert the payment. If you get hacked and the private keys for your smart contract are stolen, there's nobody who can just roll it back for you.
The OS is the weakest link - a side-channel that will bypass any and all clever cryptocurrency designs.
