You may be rare, or haven't done much yet. I've been in software dev in some capacity for about 17 years, and have been stiffed myself a couple of times, and I've had companies I've worked for been stiffed too. In some cases it was for a lot of money, in some cases very little. If it hasn't happened yet, it probably will at some point. It's not guaranteed, but I don't think I know anyone that's been at this for more than 5 years that hasn't had client payment issues at some stage.