Saudi Arabian entrepreneur Essam al-Zamel has overcome many obstacles to found a string of technology companies in the past decade, but he thinks sliding oil prices will be hard to handle. "A black economic cloud is covering the skies of Saudi Arabia," Zamel tweeted last week, warning that prices might not recover for five or 10 years.
Oil's drop to six-year lows, less than half mid-2014 levels, is beginning to sour the business mood in the world's top oil exporting nation. After a decade of sky-high oil revenues and rapid growth, Saudis are grappling with the idea they may be entering a long period of more modest economic circumstances.
That realisation is reflected in a tumbling stock market and a public debate about the kingdom's economic future - some of it coming close to criticising government policy, which is unusual in a country where dissent is tightly controlled.
"Over the past 10 years, expert advice has been ignored. The economic system did not heed it and preferred to sleep on the cushion of the oil boom," tweeted prominent economist Abdulhamid al-Amri.
Saudi Arabia must wean the private sector off an addiction to oil-fuelled government spending and curb speculation in the stock and real estate markets, which is widening social inequality, he wrote.
Other economists and businessmen are urging officials to do more to diversify the economy, reduce the kingdom's dependence on millions of foreign workers, and restructure state spending.
Consultant Fawaz al-Alami wrote in the Al Watan newspaper that instead of issuing bonds to finance itself in an era of cheap oil, the government should save money by cutting subsidies that keep electricity prices low - a politically sensitive reform from which authorities have so far shied away.
RESERVES
Financial reserves mean Saudi Arabia is far from crisis. With Brent crude at $45 a barrel, the government is running an annual budget deficit near $150 billion - but it has over $600 billion of foreign assets at the central bank and little debt.
That means Riyadh can still spend to support the economy, which appeared to grow strongly in the second quarter as Saudi Arabia boosted oil ouput, partially offsetting low prices.
A consumer boom has continued, helped by a salary bonus to state employees in January to mark King Salman's accession to the throne. Major retailer Jarir Marketing reported a 9 percent year-on-year rise in second-quarter sales.
Nevertheless, many Saudis fear handouts such as the January bonus may not survive in an era of cheap oil. This belief has contributed to a 16 percent stock market plunge in August, destroying $65 billion of value, and could start to dampen consumer spending.
The government's secretive management style has stoked anxiety. Finance Minister Ibrahim Alassaf declared in May that the kingdom's financial position was very strong and Riyadh would spend on development projects to stimulate the private sector. But top officials have publicly given few details of how they will handle an age of low oil prices.
This has left businesses guessing. In July the government began issuing bonds for the first time since 2007 but it has not revealed its projected borrowing requirement, so bankers worry about an eventual liquidity crunch.
The absence of official statements on policy leaves markets open to speculation. Stocks were hit this month by talk the government might sell share holdings to raise money; state news agency SPA finally denied the rumours last week.
Consumers and businessmen wonder if they will face new taxes and fees. Last week the International Monetary Fund urged Riyadh to alter domestic energy prices, curb public sector wages, and introduce value-added tax and land tax in coming years.
Many economists think such policies are probably inevitable in the long run. But Saudi officials did not respond publicly to the IMF's advice, so it is not clear when or even if the government will summon the political will to act.
The rigid, top-down structure of the government can make economic policy changes difficult, said a Saudi banker. "Everyone is having to wait for direction."