> Where do people get this knowledge?
Time, hands-on experimentation, and focus.
Anecdotally, reverse engineering and low-level hacking felt more popular back in the 90s and early 2000s. Back then, there were fewer distractions to soak up the free time of young tech enthusiasts. Old IRC chatrooms feel like a trickle of distraction relative to the firehose of Twitter, Reddit, 24/7 news cycles, and modern distractions.
A common complaint among the younger engineers I mentor is that they feel like they never have enough time. It's strange to watch a young, single person without kids and with a cushy 9-5 (or often 11am to 5pm at modern flex/remote companies) job complain about lack of free time. Digging deeper, it's usually because they're so tapped in to social media, news, video games, and other digital distractions that their free time evaporates before they even think about planning their days out.
It's amazing what one can accomplish by simply sitting down and focusing on a problem. You may not reach the levels of someone like Alyssa, but you'll get much farther than you might expect. And most importantly, you probably won't miss the media firehose.