Because Prolog bends your brain and getting your brain bent is fun. :) In the real world there are few applications of Prolog. Part of the reason is that Prolog

Because Prolog bends your brain and getting your brain bent is fun. :) In the real world there are few applications of Prolog. Part of the reason is that Prolog doesn't mesh very well with functional programming constructs which are very popular in data processing. Another part of it is that the execution model doesn't match many real world problems. For example, in a document retrieval system you might want to find the 10 documents that most closely match an input query. Describing that as a constraint programming problem (Prolog excels at those) is not easy.