For me it's a few things. Primarily I've always loved playing pinball. Now that I'm an adult I can collect, restore, and preserve the games I remember playing as a child. There is also a great sense of satisfaction that comes from bring a game back from the dead. I guess I consider my self a steward of the 80s & 90s arcade era. Protecting and caring for the machines because they cannot be replaced.
There is another factor too. I suffer from pretty bad anxiety. I don't even think that I was aware of it until a year or so ago. I just thought that everyone was like me. But they're not. Everything is so fragile in my mind always on the brink of destruction, or decay. So taking these machines (which I am fond of regardless) and protecting them, caring for them, and preserving them allows me some sense of control over that. While I'm working on them nothing else is on my mind. It's just the machines and I. Nothing to be stressed about. So the sense of stewardship and calm is hugely therapeutic in a way.