I once worked for a billion dollar retail company. Their core back office applications (sales tracking, logistics, orders and fulfillment, staff rosters, etc) were written in COBOL and the inputs and outputs were read from / written to temporary files; kind of like pipes but via temp files in case of job failure. The real problem was that there were about 3,500 COBOL programmes and 2,500 shell scripts all in one directory. All the executables, COBOL and shell alike, were given a 4 digit filename; there was no up to date documentation on what program did what (apart from the source), or in which order they should be run, or the dependencies there in. To top it off end of day processing would take between 12 to 16 hours to run; any major problems and it would start affecting the next day's EOD. There was only one guy in the office (who had been there 15 years) who understood how it all fit together; when he died things got much worse (no he wasn't that old, how he died is another whole war story all together).

I only lasted there 6 months before I left for a start up, in many ways it was too much to bear. A while after I left taxation for retail changed substantially, there was a massive IT stuff up and the billion dollar business wound up being carved up and sold off; several thousand jobs affected, many lost their jobs either directly or indirectly as a result.

Sure this is probably at the worst end of the scale (short of causing deaths) and is rare but it does happen. Billion dollar company succumbs largely because of IT failures. It got to the point that the cost of the technical debt was higher than the carve up losses...