If you’re a programmer of any kind and have done it for any length of time at all; particularly as your profession, not just a hobby, you know this one rule:
Good programmers expect things to go bad.
One of our prime directives as lord or lady of the bits and bytes is to predict what can go wrong and prevent it. Or at the worst case, handle it gracefully.
Being a developer isn’t exactly all baby giggles and sunbeams so a healthy amount of pessimism is certainly warranted.