>>7distributed systems are never ``strong''
Here's how to have a secure distributed system:
1. don't have a distributed system
Besides, security isn't the only concern. You know what else you need to worry about? Performance and energy usage. Cryptocurrencies are slow as fuck to process transactions and use a ton of energy thanks to people mining with ASICs or GPUs. Additionally, a public transaction ledger means there's no security, unless you only use cryptocurrency over Tor, but Tor is slow as fuck, and you also have to worry about malicious nodes (which there are actually plenty of).
Blockchain is a meme-tier buzzword used by tech startups who want a quick exit game. Create a shitty derivative cryptocurrency that's like a shitty version of Bitcoin that nobody uses, then cash out. It's a ``greater fool theory'' shit. See also: tulip mania.