A more conventional education really is no guarantee against a different set of holes, but holes nonetheless.
I was once brought into a project at a very large insurance company. A project rollout had been delayed well over a year because the code just kept crashing after a period of use (1-2 hours). The software did what was intended, but was pretty unstable, I was told. The longer it was used, the more likely it would bomb-out.
Nearly the entire project team was in a giant meeting when I arrived. I got there at about 9am, was shown to a cubicle, and told to just hang-out. After an hour or two passed, I went looking for trouble. I found a guy I recognized (also from Cap) in an office on the other side of that floor, and he showed me the code. He was lobbying for a rewrite from the ground up. Ugh. BTW, this guy had a masters from a good school.
Looking at the code, I spotted the culprit in about five minutes. They were testing for whether a file existed by masking errors and attempting to open the file. What they didn't do is, close the file if they had successfully opened it. So within not much time at all, they would simply run out of available file handles.
BTW, that bit of code had been copied straight out of the reference manual for the compiler they were using (bad technical manuals were the norm).
I pointed-out the error, and told the guy to add a couple of lines to close the file if it was successfully opened, and announced I was leaving. I got home and the phone was ringing. The account rep. that sent me to the client said everyone was upset that I had left. I told him I had fixed it and wanted to work on another project from home (for a client that was out of state). If they were that upset, I told him, they didn't have to pay me.
After my rep. pushed me a little I told him the truth: I was immensely embarrassed for these guys, I didn't want a face to face. I didn't want to be there for the stages we'd go through, which would be denial mixed with anger, acceptance mixed with embarrassment, and ultimately excuses and finger pointing.
I did get paid, BTW. It was a thirty day assignment, subject to extension. I was paid a full thirty days wages, my rep. saw to that.