If it costs you $X to add 32Gb of RAM to your machine, it will cost an attacker $X * 1000 to add 32Gb of ram to a GPU - GPUs do not come with 32Gb of RAM today,

If it costs you $X to add 32Gb of RAM to your machine, it will cost an attacker $X * 1000 to add 32Gb of ram to a GPU - GPUs do not come with 32Gb of RAM today, so it has to be custom hardware. To sum this up, it's one of those ways to make sure that attacker's cost grows much faster than defender's costs, but it's not without cost to the defender.