Protests over economic grievances are hardly new in Iran: riots over inflation in Islamshahr and Mashad in the 1990s, frequent strikes by the bus drivers union in the 2000s, protests by schoolteachers over unpaid wages. Those voices were barely heard. They came from the bottom of society and were either stifled halfway through by the government or drowned out by civil rights activists with better access to the international media. They have now forced their way to the surface and emerged as a resonant, nationwide cry for justice and equality.

Since the 1979 revolution, Iranian politics has been defined by a split between reformists and principlists, conservatives who say they are devoted to the principles of the revolution. During the 1999 and 2009 uprisings, the protesters enjoyed support from powerful reformists. This time, the dichotomy has been transcended. The demonstrators don’t want support from anyone associated with the status quo, including Mr. Rouhani, the reformist president. No wonder prominent reformist figures, even Ebrahim Nabavi, a dissident journalist living in exile, disparaged the protesters as “the potato-eating mob.”

Iranian economists and intellectuals have long warned that something like this could happen. Even the figures relatively close to the government set off the alarm. In early 2015, Mohsen Renani, professor of economy at the University of Isfahan, wrote an open letter to the Guardian Council, Iran’s highest clerical body and one of the country’s most powerful institutions, expressing deep concern over rising inflation and government incompetence. Mr. Renani predicted that if issues like growing unemployment were not addressed within two years, Iran would face turmoil. Parviz Sedaghat, another prominent political economist, published an article just before the protests broke out discussing how Iran’s economic system has produced first-class and second-class citizens, and warning that some government institutions have become economic conglomerates more powerful than the state. A detailed study published last month by the BBC’s Farsi-language service demonstrated the alarming decline of household income over the past decade. Mr. Rouhani’s austerity budget, submitted to Parliament on Dec. 10, only poured fuel on the rising fire.

Unlike during the first decades of the post-revolutionary Iran, the rich now heedlessly flaunt their wealth. Until the mid-2000s, the gentlemen’s agreement among the embezzlers held that they keep a modest appearance at home and launder their money in Dubai and Toronto. In the most famous case, Mahmoud Reza Khavari, the former managing director of Bank Melli, made off with hundreds of millions of dollars and became a real estate mogul in Toronto. That generation cared about appearances and never dropped the veneer of fealty to the ideals of the 1979 revolution. Their millennial offspring, on the other hand, hardly care. Wealthy young Iranians act like a new aristocratic class unaware of the sources of their wealth. They brazenly drive Porsches and Maseratis through the streets of Tehran before the eyes of the poor and post about their wealth on Instagram. The photos travel across apps and social media and enrage the hardworking people in other cities. Iranians see pictures of the family members of the authorities drinking and hanging out on beaches around the world, while their daughters are arrested over a fallen head scarf and their sons are jailed for buying alcohol. The double standard has cultivated an enormous public humiliation.

The people today at the top of power pyramid in Iran were involved in the 1979 revolution and witnessed firsthand how, when the shah decided he had “heard the voice of the revolution,” he marked the beginning of his end. That impression has been reinforced by the Arab Spring: Zine el-Abedine Bin Ali of Tunisia and Hosni Mubarak of Egypt tried to appease protesters and were forced from power. Bashar al-Assad of Syria never even recognized the existence of opposition and he remains in office.