Qualcomm is more or less a research company, the main cost of their business is paying engineers to build their modems/SoCs/processors/whatever.
They have been working with ARM for the last, I dont know, 20 years? Even if they manage to switch to RISC-V, and each employee has negative performance impact of like 15% for 2-3 years this ends up in billions of dollars, because you have to hire more people or lose speed.
If corporate would force me to work with idk Golang instead of TypeScript I could certainly manage to do so, but I would be slower for a while, and if you extrapolate that on an entire company this is big $$.