I came here to say "can we worry about building programming languages in twenty-four years instead, please?". Someone who has gone through your list is exactly who I want actually building the next generation programming languages. Of course your last question is the best one:
> eh, why bother
This is absolutely the question you need a deep answer for. You need a problem that is burning you up and whose only solution is a new programming language. This might never happen. If it ever does, you're the person to do it, exactly because of all the ups and downs and half-started ideas you've thrown away. But you're right: the "why bother" stage is not to be ignored. It's the most important one.
I had to change the scope of my desires. I don't want to make the next Python. Not even the next Zig or Nim. I just like fiddling with compilers and interpreters. Someone else mentioned Crafting Interpreters and I'll bring it up, too. I've been following along in C# and occasionally come back to my C#Lox implementation and work through another chapter. It is quite a lot of fun.
I implemented VBA in C# a few years ago for malware analysis, and my takeaway is...well, it's a hard project. Possibly as hard as I've ever done, but a big part of that was guaranteeing bug-for-bug and type conversion compatibility and obscure language features that nobody would include today. I can't even fathom how the old folks implemented BASIC in 256 bytes of 8-bit assembly back in the day.
- Be armchair-interested in programming languages
- Take some PL-whatever courses in college
- Read about PLs
- Read about progressively niche PL stuff…
- Get idealistic (get ideas)
- Read about the grueling design process of useful-in-the-real-world languages
- Eventually realize that There Are Always Tradeoffs
- Realize that the Tradeoffs are like two thousand parameters that might interact in super-weird and non-obvious ways
- Realize that a dozen super-competent PhD-wielders and multi-decade practitioners can easily spend a decade on developing the core of a language
- eh, why bother