That's an interesting point - passion does fade over time. I spent 10 years of my life intensely devoted to music, but at some point it just evaporated. It's baffling, really.
As for software development, I found my passion as a kid when my father taught me some simple scripting on his old Dolphin. I was simply amazed by the vast landscape of possibilities.
maintaining passion over a longer period of time (turning the hobby/passion into a career) is much harder than finding it. it requires a routine with a rule to restrict/timebox the joyous activity as much as one timeboxes the chores.
Hunter S. Thompson’s Letter on Finding Your Purpose and Living a Meaningful Life https://fs.blog/2014/05/hunter-s-thompson-to-hume-logan/