How can people be so stupid?.

Easily, Frank

It's true of burglar alarms too, according to the chap who serviced mine. 1066 was one of the most popular numbers. People also often use their own telephone number.

Equally, the passwords people use are often easy for the criminally minded to guess: spouse's or children's names, dates of birth, pet's name, street name, etc. And people don't change them regularly.