When I first heard of Cryptocurrency my friends told me my money would be more secure in crypto than the traditional banks and that I would be my own banker. So I opened a wallet only to hear that some person’s accounts were hacked.

So I made a few studies on how secure blockchain technology is. Below is my finding;
Hacking a blockchain is nearly impossible, but an open blockchain network has hubs and utilizations the Proof of Work (POW) consensus algorithm. If a hacker gains enough computing power to control more than half of the total computing power on the network, (POW) can solve the required cryptographic puzzles faster than other nodes. Note that this node uses special hardware and software representing the transaction verification method of the POW algorithm. Once hackers have a higher hash rate (computing power), they can manipulate transaction history and cause twofold spending.

According to MIT Technology Review, less popular blockchains have fewer nodes, making it easier for hackers to launch 51% of attacks. In 2018, hackers attacked a relatively new cryptocurrency network with a small number of nodes. You can read the MIT Technology Review report to know more. Some coins like Monacoin and Bitcoin Gold fell victim to these 51% attacks.

Having known this I will be grateful if further contributions can be made on this subject of discussion so I can learn from more experienced persons.