This is a tool to explore the viability of an attack on the SAFE network. An attacker must spend money to attack the network, and the chance of that resulting in some benefit determines whether the attack is viable or not.
A larger SAFE network means a) more attacking vaults are required so the cost is higher and b) less safecoin can be stolen per section so the benefit is less.
This chart shows the maximum price of safecoin for a specific network size before an attack becomes viable. More info.
If the price goes too high an attack becomes viable.
The price should always stay below the line to prevent an attack.
This model is heavily simplified and there are many factors that may cause differences between real life and the model.