Games

The problem is that hardware has come a long way and is now much harder to understand.

Back in the old days you had consoles with custom MIPS processors, usually augmented with special vector ops and that was it. No out-of-order memory access, no DMA management, no GPU offloading etc.

These days, you have all of that on x86 plus branch predictors, complex cache architecture with various on-chip interconnects, etc... It's gotten so bad that most CS undergrad degrees only teach a simplified subset of actual computer architecture. How many people actually write optimized inline assembly these days? You need to be a crazy hacker to pull off what game devs in the 80-90s used to do. And crazy hackers aren't in the game industry anymore, they get paid way better working on high performance simulation software/networking/embedded programming.

Are there still old fashioned hackers that make games? Yes, but you'll want to look into the modding scene. People have been modifying the Java bytecode /MS cli for ages for compiled functions. A lot of which is extremely technically impressive (i.e. splicing a function in realtime). It's just that none of these devs who can do this wants to do this for a living with AAA titles. Instead, they're doing it as a hobby with modding instead.