It's a rational conjecture that hunters tend to strive to continue winning the intelligence arms race over prey, and that technology tends (but not always) is an emergent property from this set of species.
It's also possibly to do with their lack of shell. While other molluscs have a shell to protect them Cephalopod do not, perhaps this forced the evolution of a more capable brain.
This. The cuttlefish (a relative) changes the color of it's skin and texture to hide from hunters/prey. If you have not seen this video, prepare to be amazed: https://www.youtube.com/watch?v=PmDTtkZlMwM