What Is the Relationship between Coin Difficulty and Vulnerability to a 51% Attack?

Coin difficulty is directly related to the total hash rate securing the network. A lower difficulty generally means a lower total hash rate is currently mining the coin.

When the total hash rate is low, an attacker needs to acquire significantly less computing power to achieve the 51% majority. This makes low-difficulty coins highly vulnerable, as the economic cost to launch an attack is much lower.

High-difficulty coins, like Bitcoin, are prohibitively expensive to attack due to their massive hash rate.