If (CPC * ConvRate * CLV) > CPC then you can pay those prices. Granted, it's not entirely that simple with payback periods to consider, but big advertisers like

If (CPC * ConvRate * CLV) > CPC then you can pay those prices. Granted, it's not entirely that simple with payback periods to consider, but big advertisers like insurance companies have plenty of money to fund acquisition until it pays back.