Mention has been made that although the flight was not full (with 50 or more unoccupied seats) there were passengers who flew standby. The reason given for this in this thread was that cargo uplift may have limited passenger capacity.
Question - how often does routine cargo on a passenger flight displace this much passenger uplift capacity?
If it was revealed that the cargo included a heavy valuable substance weighing as much as 50 passengers and their baggage, how many reading this thread would change their mind as to likely cause?