Earlier quoted context omitted.
Designing a new clean and better ISA is easy. With the current existing experience that could be done in weeks or a few months at most, to allow for the simulation of how various variants run benchmarks, to determine the best variant. Nevertheless, designing the ISA is the only easy part. Then you have to write high-quality compilers, assemblers, linkers, debuggers and various other tools, and also good documentation…
Interesting to see RISC-V described as an "incumbent" :D
It has already entrenched itself in the industry.