I find that many people have surprisingly strong mathematical backgrounds.
I just learned that the new pope, Pope Leo XIV, holds a bachelor’s degree in mathematics from Villanova University in Pennsylvania <
https://catholicreview.org/chicago-native-cardinal-prevost-elected-pope-takes-name-leo-xiv/>. No doubt there are many other people who have a significant mathematical background that you would not immediately guess.
I've often wondered how to find these people to see if they might be interested in working on Metamath proofs. Not the new pope specifically (I bet he's busy right now), but others who might be interested in using their knowledge on the side to work on such proofs. If anyone has ideas on that, I'd love to know!
--- David A. Wheeler