My dad collected muscle cars (primarily GTOs) in the 60's and 70's, quit his beneficial finance job and worked in a body shop and up thru the ranks until he was GM of a large multibrand dealership when he died. That was my exposure to iron and the really cool stuff people really liked. My grandad was a machinist for westinghouse (back when they were a real company that built real things HERE) and I spend weekends with him, thats where I learned what a 3/8ths-16 is and what size drill to get 84% thread from a tap.
join the two together and i had my own grass cutting service as a teen with my own maint department, fixed and raced all my minibikes and such, ditto the 3 wheelers.
I hedged my EE/CS in college with a stint at the GM tech school and worked on the side or at dads dealership during college since until I hung my own shingle in 1999. In 2004 I worked for Centroid and got the automotive 'division' going - using CNC machines to do engine things.
It all adds up over the years - the knowledge, the tools, the 'proven parts' piled up in sheds.
Sadly, joe driver does not rebuild his engine nowadays, he just 6-8year finances a replacement ride. So I dont get to exercise my forte as much as I like. I dont have employees in the shop anymore since the crash a few years back, and I only do it on the side with my day job keeping me busy. suffice to say 'funny noises from the transmission' do not scare me.