Are fighter jet cabins pressurized?
Cabins of fighter jets are in fact pressurized, but not same as the passenger airplanes. Cabin pressure in a passenger airplane will increase (almost in a linear fashion) as the airplane climbs. However, fighters keep ambient air pressure to a certain altitude. It maintains this pressure until a certain pressure differential is met, and then cabin altitude increases to maintain this differential.

Therefore at higher altitudes, cabin pressure in a fighter jet is low enough that supplemental oxygen is required for the pilot(s). This is supplied via On-Board Oxygen Generation Systems.

By not pressurizing the cabin completely reduces stress on air frame and is beneficial during an unplanned decompression.



By the way, your friend (military fighter pilot) is correct.