The sale of the century has ended in farce. The modest sums raised from the "privatisation" of Saudi Aramco will barely cover the kingdom's fiscal deficit for six months. The $US25 billion ($37 billion) haul will not make any impact on Prince Mohammed bin Salman's Vision 2030, his theatrical plan to break oil addiction and diversify into everything from car plants to weapons production. Nor will it go far to launch NEOM, his robotic half-trillion dollar white elephant on the Red Sea.

Saudi Crown Prince Mohammed bin Salman's IPO has not gone to plan. Credit:AP

At least there was doubt before about the predicament facing the House of Saud. Now there can be none. The regime resorted to tricks just to sell just 1.5 per cent of the shares on the local Tadawul exchange: a "Ritz Carlton" shake-down of princes; doubling the bank leverage limit for Saudi retail customers so that they can buy the stock; and calling in diplomatic chips from the Gulf alliance.

Other foreigners will not touch Aramco, even after the prestige valuation of $US2 trillion was trimmed to $US1.6 trillion - $US1.7 trillion. Theoretical oil reserves are not worth much these days as the climate backlash gathers force, and Aramco carries a special discount as the opaque political instrument of a headstrong master.

Riyadh needs every dollar of current revenue to pay for its cradle-to-grave welfare system, to cover the world's fourth biggest military budget and the war in Yemen, as well as bankrolling Egypt. This is an extraordinary cost edifice for a middle-income country like Saudi Arabia, with a per capita income similar to Greece.