Creating a "new" programming language isn't that difficult - creating something that is interesting, elegant and/or powerful requires a lot of thought and that is difficult.
For me, creating a new programming language which is suitable for general purpose programming would be extremely hard, regardless of how novel or good it is. But, fair point that "hard" is always subjective.
I think I was being over literal about the "language" part - it's certainly possible to create a very simple language in a short time but actual productivity would require a lot of libraries and tooling and I suspect that is much more work than the core language.
