Pray tell, what advantages would the powers that be gain by killing off/injuring the vast majority of the productive class of mainstream citizens? Doing so wou

Pray tell, what advantages would the powers that be gain by killing off/injuring the vast majority of the productive class of mainstream citizens? Doing so would devastate the economy, bring technological progress to a quick halt, and result in enormous and unpredictable public response. I see no gain in it for them. Do you?