This is exactly what they are doing.
Lots of people are buying GPUs, but any SINGLE gpu coin has a very small percentage of total GPU hashpower.
For the extreme case, image that I have GPU coin, but I am only supporting it with MY GPU.
That means that any other person in the world, can now attack my coin, if they have more GPUs than me (1).
The fact that lots of people own GPUs doesn't protect me, because those GPUs aren't contributing to the network!
This is exactly what they are doing.
Lots of people are buying GPUs, but any SINGLE gpu coin has a very small percentage of total GPU hashpower.
For the extreme case, image that I have GPU coin, but I am only supporting it with MY GPU.
That means that any other person in the world, can now attack my coin, if they have more GPUs than me (1).
The fact that lots of people own GPUs doesn't protect me, because those GPUs aren't contributing to the network!