1. No. 'Graphics programming' just like all of those other examples is split into two branches: those who make the libraries, engines, SDKs, and drivers (Microsoft, Nvidia, Unity, etc.) and those who use the libraries to make end-user applications (game developers). Doing DX or OGL/Vulkan work is just a bunch of function calls, and if you're using someone else's engine it's even more abstracted than that. They're all more or less equivalent in terms of complexity, and highly variable across the industry. A couple of guys trying to bolt together something for their crowdfund campaign are going to care about time consuming, magic-prone performance optimization a lot less than a company like Cloud Imperium that hired a bunch of former game-engine gurus to push the envelope.
2. Carmack is not simply 'competent' he's a living god of black magic programming with few equals before or since. His particular type of genius is also one that the typical programmer doesn't even need anymore, due to all the aforementioned libraries that didn't exist in his day. A programmer aspiring to be as good as John Carmack is like a guitarist aspiring to be Joe Satriani: a lofty and worthy goal, to be sure, but your career isn't DOA if you wind up being merely capable. Like other disciplines, it takes about 15 years to be fully qualified to lead a project, 5 years to lead a component or subsystem, and a few months to make meaningful contributions to a project.
3. C++ is still good, and if you don't want the new stuff there's nothing forcing you to use the newer versions. A typical project may also use a combination of C++ and other things, since compiled deliverables have moved away from a single monolithic .exe file toward a collection of libraries and processes that talk to each other.
4. It's no secret that the big studios don't treat their staff very well, but the pay is usually good for that line of work and they'll keep doing it as long as the seats stay filled. Not all game developers are sweat shops, though. This again mirrors the larger industry. The best way to not get treated like a serf is to stay away from places that are saturated with young nerds who'll do anything for their first or second job.
Note that I do mostly embedded C++ with some .NET and HTML/Js on the side, I wrote a very basic DirectX based rendering engine in high school and messed with OpenGL some in college but nothing serious. So I have some experience but I'm not a professional game dev guy.