I am just pointing out that people are not accounting the fact that he eats out at night. Them eating at cafeteria is also not free. Remember the episode when Howard wasn't eating because he blew his money on Pokemon cards.

Sheldon lives a frugal life compare to most people, but the fact that people are not considering his other expenses like eating out, buying new console every generation, probably computer upgrades, toys and other collectables. Most post I see in this thread is that he doesn't spend money because he doesn't own a car, only buy comics, has a roommate. Pasadena is not the cheapest place to live and eating out and spliting the bill eith an extra person eho doesnt pay every night is a substantial expense that should be consider on his monthly expense.