There is no one-size-fits-all answer to this question, as the best reason to hire a Happstack developer may vary depending on your specific needs and situation. However, some potential reasons to consider hiring a Happstack developer include: - They have experience building web applications with Happstack. - They are familiar with the unique benefits and features that Happstack has to offer. - They can help you take advantage of all that Happstack has to offer, including its scalability and extensibility.