13. Most programmers think they know what they're doing but actually are "incompetent". (There are Usenet posts going back to 80's documenting this fact.) How am I defining "incompetent"? In my definition it means writing software that any reasonably skilled hacker can cause to "malfunction", i.e. not perform as expected by the programmer, which depending on the program may or may not present a security risk. The number of "competent" programmers i.e. those whose programs are immune to the acts of reasonably skilled hackers, is very small. They are a rare commodity. In sum, there's lots of reasonably skilled hackers and very few competent pogrammers. There is no licensing body for programmers. Anyone can call themselves a "professional programmer".

Note: If a programmer only writes programs for her own use, "competency", as defined above, is all but irrelevent. Whatever works.

Controversial, but true.