They are often paid to create these things, by their employers. They then open source them to in the hope of getting free engineering resources from other companies that care about the same thing.
Operating systems and programming languages do come in the cool catagory
Every one of those things falls into the cool category for some subset of the programming population.
There are very good open source databases, content management systems, web servers, full text corpus search systems, operating systems, and 100s of other "kind of boring" things that a 20 year old version of me would assume people would need to be paid to create. (Some of those are a crossover where a substantial portion of the development was originally paid, of course, but many others are not.)