Grew up with a mechanic father and spent many hours as a little kid watching and helping build/restore all his cars and repair family member's cars all the time. Basic maintenance like oil changes I just knew how to do like an infant learns to cry. I’m just an engineer type personality through and through; favorite toys for years where legos and this 160 in 1 electronics kit, I was a DOS 2.11/GWBASIC wiz around 8 and I always took everything apart (fondly remember trying to run dual processors on a 8088 XT board by sticking a second 8088 in the empty 8087 slot, hey I was 8).
I remember being given a junked 4 bbl carb one day when I had to stay with my dad at his work in an attempt to keep me occupied, about 6-7. Had it completely apart and back together in an hour much to their dismay. Pretty much grew up around grease, garages, and gasoline fumes, even though I wouldn’t tap into that experience until much later.
It was because of that I wasn't interested in cars at all when I got older, I was into electronics, computers, programming and didn't really care for car stuff because I was around it so much that I took it for granted. But after I was older and had been driving for a while in a plain jane car and realized how much of a douche people can be just because their car is faster or more nicer, I started yearning for some something shiny myself, and muscle like the cars I rode in before I could drive (or reach the pedals even) became first on the list.
On top of that, my interest in computers for the sake of computers faded, as I wanted to DO SOMETHING USEFUL *with* computers (eg: embedded control systems), and cars today are all computer.... thus a convergence occurred. And as always what started out as a simple material obsession or envy turned into a legit money eating personal passion.
Manuals. I always had my nose buried in manuals to something, whether it was a repair manual for an engine or those boxed MS/IBM binders with DOS manuals that came with old computers back in the day. I always loved the exploded diagrams of the internals.
Pretty much once you learn ONE of ANY kind of engineering discipline, be it computers, cars, whatever, learning others is pretty easy when you have a natural tendency to understand how things work. Think about how you learned how to use a computer. The biggest thing that holds people back is fear. Fear of breaking it, fear of not being able to put it back together, fear of getting dirty. Screw it, dig in and figure it later.
I think many people see stuff they don't understand as some kind of fragile princess and they don't want to risk making a mess of it or getting things ugly. Trust me, no matter how ghetto you think are trying to work on your own car for the first time, or how scared you are of beating on something with a big f**king hammer on your pristine clean shiny pride and joy, or how wrong it seems to use a nasty 2x4 to pry on the engine or suspension in your delicate $30,000 piece of "advanced technology": It's already been done somewhere in a profressional shop by someone with 30 years experience and every tool known to man. That includes YOUR car at some time when you pay someone else, and what you didn't know didn't hurt then, and it won't hurt when you do it yourself. Anything can be fixed if you break something; it just might cost a little more money for a lesson learned, that's all.