You can say it was luck but it was definitely not "average".
Nvidia thrived because it paired great hardware with great software.
AMD and Intel think hardware is enough; it’s not. There’s a reason neither has ever been able to compete with Nvidia.
They have a giant ego, but I’d argue it’s probably well deserved.
Apple is/was similar. They also see that hardware without great software is useless. Spend as much; if not more on software to make your hardware shine.
Yeah, it pretty much does. CUDA is why they are positioned where they are. Other players like AMD and Intel could have done that, but they didn't, and if they had, they wouldn't have persevered for 10+ years with essentially nothing to show for it.
Whether CUDA will continue to maintain dominance is less clear. It may become a literal victim of its own success, as CUDA-based models gain the ability to migrate themselves to new platforms.