Secure systems need random numbers (RN).
RN generated arithmetically are pseudo-random, and not safe, e.g. middle squared of V. Neumann which is unsecure because its predictable (every number depends on the previous seed).
In Cryptography, pseudo-random number generators are designed to be unpredictable no matter the sample, which is critical. Seeds based on timing can be guessed and cracked. SSL web navigation, WiFi, etc. establishes a master secrete key to exchange information.
Truly random numbers can only come from mathematical processes such as radioactive decay, flow, atmospheric noise, cosmic rays, and other chaotic sources.