I have a coworker like that too, my pet theory is that they're not passionate about their job to begin with. It's just something that can pay their bills.

While waiting for Claude to finish, we talked about our hobbies outside of work, and the same guy will go into deep details on how steroids and the HPG axis works, and even gave me a spreadsheet with several NCBI PubMed links on the topic.

I think we are all naturally be more creative and opinionated in things we are interested in.