Systemic risk can, over the long term, be changed by changing the system or culture.
It can be changed up or down.
I agree the systematic risk can be lowered - a combination of greater concealed-carry and citizen vigilance and other things had lowered the overall level and rate of crime in the US over a number of decades. It is a slow process but it is possible.
....but you can't eliminate the systematic risk. That's the stated goal of NZ - eliminate COVID19. It is as foolish and unrealistic as zero drugs and weapons in prison...and prison is, like NZ, a theoretically self-contained system.
Years ago, I read an article from a liberal Mom who banned toy guns and violent entertainment from her home. She expressed her shock - then subsequent acknowledgement of reality - when she saw her kids had bitten their morning toast into handguns and were shooting each other.
Prime Minister Arden has a lot to learn.