Private investors have incentives to invest in the non traded goods sectors because they expect demand for non traded goods to increase in the future when the country begins to spend its oil revenue. The global price of oil has important consequences for national income.
In essence the bulk of the national income derived from oil takes the form of public revenues, because the oil companies themselves are foreign. Production sharing agreements in the oil industry are structured so that most of the risk of price volatility is borne by public revenues.