In the context of continuously evolving tech industry demands, consider a scenario where a software developer has to choose between dedicating their time to learning a new programming language that is rapidly gaining popularity in the field of data science, versus investing time in a personal project that involves integrating advanced API functionalities into an existing application. How should the developer prioritize their learning and project work, balancing the acquisition of this new technical skill against the practical application of their current skills in a real-world project? Furthermore, what factors should the developer consider in making this decision, given the dynamic nature of industry demands and the importance of both hard and soft skills in their professional development?