One reason is it's a discipline that you can't really start in college. Unless you have a fair amount of tech experience of some sort under your belt by then,

One reason is it's a discipline that you can't really start in college. Unless you have a fair amount of tech experience of some sort under your belt by then, you'll never be more than mediocre. Ideally, it's experience you got by scratching and clawing. If someone served it up to you on a platter, it's not going to be worth much. It probably doesn't help that people are being directed into the field for reasons other than that they simply really want to do it. Those people will fail at a high rate. Finally, as many have observed, there's a knack to it. If you don't have it, you're not going to do well. (I lack the knack for a lot of other fields, and having tried a bit, there's not much way to get past that.)