I've come across cases,where people claim that their blockchain was hacked and a huge amount was stolen from it, and I find it hard to belive it's possible because in my opinion it's impossible for a blockchain to be hacked because it's decentralized (not controlled by any authority) and it's managed by it's users
To be honest, the concepts underlying blockchain technology make hacking into a blockchain nearly impossible. Nonetheless, there are flaws outside of the blockchain that allow thieves to exploit. Hackers can steal blockchain by gaining access to cryptocurrency owners' Blockchain wallets and exchange accounts.
I have few cases I can use to demonstrate that hackers can gain access to blockchains in certain circumstances. This includes the scenarios listed below:
Inadequate security: Many blockchain breaches have occurred on exchanges, where users can trade cryptocurrency. Hackers will have easy access to data if the security practises surrounding the exchanges are lax.
51% Attack on Small-Scale Blockchains: For example, miners can create a forked version of the blockchain in which certain transactions are not reflected. This allows miners to build a completely separate set of transactions on the fork and claim it the true version of the blockchain, despite the fact that it is fake. This also allows the hackers to spend cryptocurrency twice. Because it is difficult for miners to obtain considerable control over larger and more complicated blockchains, 51% attacks are more likely on smaller scale blockchains.
Large scale Blockchain by creating errors: This could be increasingly common with larger, more complex blockchains. When this happens, hackers seeking for a way in can discover the flaws and launch an attack. This has occurred with smart contracts, which function on a blockchain network. If there is a security hole in the blockchain network on which a smart contract functions, hackers may be able to steal money from users without being caught because the fraudulent conduct is not reflected.