Because it is funnier to write new shiny things than boring, reliable things. I have an education in computer science, I know how to write a Paxos setup, I am

Because it is funnier to write new shiny things than boring, reliable things. I have an education in computer science, I know how to write a Paxos setup, I am fluent in Erlang. I am still very much not interested in formal systems, proofs and verified computing, because there I will spend 10x much time for the same set of features. Bugs are normal. I will live with bugs. I won't live with 10x development time lost.