How about potential and understanding of underlying tech?
Nvidia was an obvious play in 2013 with the precursor of AlexNet, AMD was an obvious play when Jim Keller was done.
Even if you took it for granted that GPU-powered deep learning was the next big thing, it wasn't obvious that NVIDIA would be the dominant player. CUDA made GPGPU programming easy at the time, but any other manufacturer could have released something better. It just didn't play out that way.
Alexnet was 2012 by the way. Shortly after Nvidia stock tanked!