isn't this a natural process of the network, becoming more secure over time though? added in with the difficulty adjustment, miners are naturally acting like an immune system, keeping itself ahead of any potential future threats to the security of the network?

If miners just statically decided to mine with GPUs a long time ago, threats to the network could have leap frogged the miners who decided not to compete with one another.

to me, miners competing = security goes up, so the miners have been incentivized to compete. System working as intended.