One day I watched a 3D engine demo in a 1KB executable file. It was unbelievable ! With my business partner we always wanted to have time to make one (not even in 1024 bytes, just one) Those guys were (and still are) amazing.
The most important thing to understand here is that these people are NOT actually that amazing! They are a wide spectrum of coders, artists and musicians of widely varying capabilities. What people do have is some very PARTICULAR skillsets. You can pick up those skills too! People will help you out if you ask! You can learn all these tricks if you want to. It takes some effort and inspiration, but it is doable for mo…
That said, if you watch some Shade Showdown competitions on YouTube you'll see demosceners effectively doing exactly that. It's quite intimidating how good they are.