Long ago (mid-90s) I had a coworker who was one of the last people alive who knew still how to program Cyborg, a 1970s-era programming/database platform that was still a legacy platform for a lot of companies. His job entailed making very small changes to the codebase and then waiting literally hours (sometimes days) for the shit to compile. He ended up being able to work from home for three different companies concurrently, making $300 an hour from each company. $7200 per day for about 15 minutes of actual work - while living in rural Texas.