I'm not an expert, but in the blockchain, not coins are stored, but the results of transactions. That is, the bitcoins exist as records in the database. Blockchain can not be hacked or faked, but you can enter a private key on a phishing site, or sign a forged transaction.
As far as I know, this data could be somehow manipulated if someone had more than 50% of the hashrate. However, it is very unlike to happen. If you are worried about your huge investment then hardware wallet is the best choice right now. As other people said, human error is the most common here. Hardware wallets help you not to expose your private key.