As others have said it's mostly the desire to learn. A lot of the brightest reverse engineering I have met started off hacking video games. They started with a desire to either understand the game or create cheats. From there they dug into the code.
Reverse engineering has a very romantic view from the outside. In actuality a lot of it is learning esoteric topics and boring concepts to be able to apply it to a single task. It takes a certain mindset to stick with it.
The main pre-requisite is being able to read and understand assembly language. From there it's operating system fundamentals, memory layout, compilers, basic understanding C & C++ and Python is popular in the RE community.
The RE sub-reddit has a good introduction for beginners.
Having a goal helps too. I tried and failed to learn x86 assembly a number of times in 2015 and then decided to focus more on modem firmware analysis instead. Sure, it's a bit of a cop-out (I can get a lot further without looking at any assembly code) but I'm slowly coming back around to reverse engineering the long way around.
One way to get familiar with assembly is to get a development board that can run bare metal code. You could even start with something that isn't x86, but is assembly. Once you complete a driver, game, or some other project in assembly, learning another assembly becomes considerably easier.
There is a mindset involved. You can get it on a 6502, if you want to, but you have to have it in order to make any real sense of assembly language, IMHO.
I have my struggles with this too, but I find it always interesting and fascinating. Goes back to the days of cracking games and opening up licenses on simpler, smaller computers.
I also believe a number of us should maintain and share these skills. It's important for a lot of basic reasons, and those don't have to be piracy, or nefarious malware reasons. It may be as simple and benign as using something we own to do something we want it to do as opposed to what it was originally intended to do.
Absolutely. Besides knowing Asm, the other thing I've noticed is that debugging/general analytical problem-solving skills --- being able to grok the code and understand its operation in general, without having written it --- is highly correlated with RE skills. Of those I've worked with, those who are highly skilled at debugging tend to have RE experience; and likewise those who can easily do RE, even if it's something like analysing a protocol/interface and writing a specification, also tend to be very effective debuggers.
I've never quite been able to shake the feeling of being born in the wrong era. I didn't start learning programming til I was 12, and I jumped straight into higher level languages. While I'm thankful for StackOverflow, I've got a bookshelf full of things like Peter Norton's Guide to Assembly just waiting for a spare week or two.
I sometimes feel I missed things too. For me, it's a better era alignment in that I was writing low level code on the simpler machines. But, I did step away for quite a while doing manufacturing, CAD, and a lot of related things.
All of which were very interesting, but my real love is programming and circuits. So, now I'm back, making progress, loving it, but also feeling a bit out of place.
It's what you do with what you have and being open to always learning. Reading Masters of Doom and Making of Prince of Persia, I was around (if a few years younger) during this time but I didn't have the drive these people did until much later. If you have the drive, then you can do great things, regardless of the era.
