Can a blockchain be hacked?

The big chains, essentially no. Almost every loss you read about happened somewhere else — an app, an exchange, a person.

Rewriting the history of a large chain would require out-competing the entire rest of the network, and the cost of that is measured in enormous sums for an attack that would destroy the value of what was taken. Smaller networks have been attacked this way; the largest have not.

Which makes the headline misleading, because the money keeps disappearing anyway. It just does not disappear from the chain.

It disappears from exchanges holding customer coins, from smart contracts with a flaw in their code, from bridges holding deposits, and — most often of all — from people, through a phrase typed into a fake page or an approval signed without reading it.

So "is it secure" is the wrong question. The chain is the strongest link. Everything built on top of it, including you, is the rest.

The red-flag checklist is the two-minute version of what actually protects you.

Last checked 19 Oct 2026.