Last week AFP reported that Italians have been queuing up outside tax offices up and down the country demanding free money. They are not trolling. These people thought that, because the Five Star Movement (M5S) won the largest number of seats as a single party in the March 4 elections, it is now in power and implementing its universal basic income policy.

This farce illustrates the Five Star Movement’s problem.

It surged in support (up 8 points from the 2013 elections) not just because Italians are angry at the status quo, but also because they see Five Star’s policies as solutions.

For its voters who are sick and tired of endemic political corruption, the Five Star Movement’s “zero cost politics” seems like an urgent necessity. In the eyes of its voters who think mass migration across the Mediterranean is a big problem, M5S leader Luigi Di Maio’s call for “an immediate stop to the sea-taxi service” should be implemented straight away. And Five Star voters, among the 31.5% of young people without a job, look at its universal basic income offer and see a much-needed, forward-thinking response to the dreadful unemployment situation.

Unfortunately, they are easy answers that cannot be put into practice without making terrible situations worse – if, that is, the M5S can even get into government with its agenda intact, or even get into government at all.

Lacking a majority, the so-called movement needs to form a coalition if it wants to take office. That will be tricky. The other parties regard Five Star with both trepidation and disdain, and so are keen to bypass it in their attempts to form a governing alliance.

But if the Five Star Movement succeeds in crafting a coalition, that won’t look good to many of its voters. Its disdain for the murky business of Italian coalition-building has long been one of its most popular distinguishing features. Meanwhile, taking office alongside other parties inevitably means ditching precious promises – especially in Italy.

The expensive policies are usually the first to go in coalition talks. But the MS5’s idea of a €780 universal basic income is not just costly; it’s unaffordable. Conservative estimates say it will cost around €15 billion per year. Italian public debt is the second highest in the eurozone, after that of Greece standing at more than €2.3 trillion: 132% of the country’s GDP – and it’s increasing by the day. The only thing stopping this tottering edifice of debt from crashing down on Italy is the ECB’s mass buying of its bonds in the quantitative easing scheme, but that’s ending soon. (Ironically – in the Alanis Morissette, as opposed to the proper, sense of the word – the Five Star Movement promises to cut the debt by 40% within ten years.)

M5S’s fellow populist party, the hard-right League (formerly the Northern League), polled better than expected, winning 17% of the vote, and it faces exactly the same problem. Its supporters may be keen on its flagship policies – a 15% flat tax and repatriation of migrants – but they’ll never see them implemented. The former has passed through the realm of policy into that of the joke: it would cost €95 billion. That’s while expelling African migrants is not just inhumane, it is also impossible: most of them come from countries that are either unwilling or incapable of taking them back.

The Five Star Movement is in a uniquely difficult position. It is the repository of far more hope than the League, winning almost twice as many votes. That’s in large part because it has the aura of novelty, unlike the League, which has already buried its populist policies in the Berlusconi coalition graveyard on more than one occasion.

With its raging anti-political verve, the M5S incarnates the widespread Italian yearning for a radical break with years of economic stagnation, endemic corruption and national decline. But it has no capacity to satiate this yearning. The words put up outside a tax office in Palermo in response to the queues asking for money – “we don’t offer universal basic income” – will remain true. And so will the disappointment they bring.