When someone controls more than half the mining power of a blockchain, they can pull off a 51% attack, a scenario where a single entity or group gains majority control over a blockchain’s network to manipulate transactions. Also known as a majority attack, this isn’t science fiction—it’s a real threat that’s happened before, and it could happen again. Think of it like a voting system where one person controls 51% of the ballots. They can vote themselves into power, cancel votes they don’t like, and block others from voting. In crypto, that means they can reverse transactions, prevent new ones from confirming, and even double-spend coins.
But here’s the catch: blockchain security, the system of rules and incentives that keeps decentralized networks honest isn’t just about math—it’s about money. The bigger the network, the more expensive it is to launch a 51% attack. Bitcoin? Nearly impossible. Smaller chains like Ethereum Classic or Verge? Done before. That’s why most attacks target low-hash-rate blockchains where mining is cheap and centralized. The attacker doesn’t need to own the whole network—just enough to outpace everyone else. And once they do, they can undo your transaction, steal your funds, or crash the price by flooding the chain with fake trades.
That’s why consensus mechanism, the method blockchains use to agree on which transactions are valid matters so much. Proof of Work (PoW) chains like Bitcoin are vulnerable to 51% attacks because mining power can be rented. Proof of Stake (PoS) chains like Ethereum 2.0? Much harder to attack—you’d need to buy over half the total coins, which would cost billions and tank the price before you even started. So if you’re holding crypto, ask yourself: Is this chain secure because it’s big, or because it’s built right?
And it’s not just about the tech—it’s about who’s running it. Many small chains are mined by just a few pools. If one of them gets bought or hacked, the whole chain could be at risk. That’s why you’ll see posts here about fake tokens with zero trading volume, scams pretending to be real projects, and exchanges that claim to be decentralized but still block users. They all tie back to the same problem: trust isn’t automatic. It has to be earned—and sometimes, it’s broken by someone who just has more computing power than everyone else combined.
What you’ll find below are real examples of what happens when trust fails. From coins that vanished overnight to airdrops that were just noise, these posts show you how to spot the warning signs before you lose money. You won’t find fluff here—just what actually happened, why it happened, and how to stay safe next time.
Double-spending attacks let hackers spend the same cryptocurrency twice. Learn how race, Finney, and 51% attacks work-and how to protect yourself from losing money on the blockchain.
