I'm sure it's not what you meant, but the argument "it makes me slower at my job and deliver less stable solutions, but I feel cool doing it" is not exactly a compelling endorsement.
I can't see anything in OP's post where he says any of that. Everything you said seems like an incredibly ungenerous reading of what he wrote.
Zig is a systems programming language. Moving from Python to Zig is a step down the tech stack, which brings with it exposure to underlying concepts and limitations that matter when writing any software, and which is especially valuable for a self-taught dev.
Where did he say he did it in work hours? Or that he did it instead of doing his job?
He used the word "yawn" to describe using a popular library without understanding the underlying architecture, not in reference to doing his job.
Honestly, I can't even see a tenuous connection between what you're claiming and what was said in the post. The man is expressing joy about learning new things, and you're... upset about this? For some reason? Weird.
Zig is a systems programming language. Moving from Python to Zig is a step down the tech stack, which brings with it exposure to underlying concepts and limitations that matter when writing any software, and which is especially valuable for a self-taught dev.