By any standards, and whatever happens, Beppe Grillo and the Five Star Movement (M5S) have emerged from Italy's general election as big winners.

Because of the way the electoral system works – favouring alliances Grillo shuns – the M5S will not be the overall victor. But projections suggested it could get more votes than any other party, and could hold the balance of power in the upper house, the Senate. "Honesty will be fashionable again," Grillo declared on Twitter, as the projections began to emerge.

But Grillo has so far refused to do deals with any other parties so small wonder markets and chancelleries view with alarm the progress of the man whose name translates as Joe – Beppe is a diminutive of Giuseppe, or Joseph – Cricket. It could scarcely be bettered as that of someone who has taken it on himself to recount uncomfortable truths, because that is also the role of the cricket in Italy's best-loved children's book, Pinocchio.

Giuseppe Grillo was born 64 years ago in Genoa and studied commercial economics. He might have ended up a provincial accountant.

His studies are the key to why he has such an acute perception of the many scandals in Italy in which politics and finance overlap, like the one enveloped its oldest bank, Monte dei Paschi di Siena, during the campaign. Grillo can read company accounts in a way few journalists and politicians can.

The year before the Italian food giant, Parmalat, collapsed in 2003, Grillo forecast on television what was to be Europe's biggest bankruptcy. By then, he was a well-established comedian and satirist. But not a particularly visible one.

His routine had started to become more political back in the 1980s as Italy sank deeper into the corruption that was to bring down its postwar political order. The result was he found it increasingly difficult to get on television, even after the so-called Tangentopoli scandals and the resulting clean-up, led by Milan prosecutors in the early 1990s.

Grillo did not pull his punches. He named names and fingered firms. He became too hot to handle in a country that was trying to turn its back on what had been brought to light.

He disappeared from the state-owned RAI in 1993. Its rival network, Mediaset, had the odd satire programme, but none was allowed seriously to target the network's proprietor, Silvio Berlusconi.

Grillo's exclusion from television is crucial to understanding the man and his success. It added yet more anger to the ranting monologues that had become his speciality. And it forced him to turn to what was then a medium decidedly outside the mainstream, founding a blog that soon became a samizdat for the young, frustrated, indignant and internet-savvy.

His readers supplied the core around which his friend and his digital guru, Roberto Casaleggio, were later to build M5S. Grillo's immensely successful blog underlines an important point about Italy's recent political history.

Twice in the last two decades, outsiders have burst onto the political scene. Both have done so by exploiting their understanding of the medium that was most relevant at the time. Berlusconi took Italy by storm in 1994 after creating a virtual monopoly of private television; Grillo has relied instead on making himself a master of digital communication.

The M5S, founded in 2009, grew out of what were initially Grillo fan clubs. Their members were encouraged to organise face-to-face encounters through the Meetup website.

Grillo's attachment to the internet and its culture remains as firm as ever. Some of his followers wanted him to break what had become a taboo in the M5S and go on a TV chat show, arguing it would give him an opportunity to convert those unfamiliar with the ways of the web. But, after agreeing to appear on Sky, he pulled out at the last moment.

Lingering bitterness over his exclusion from TV? Or, as his critics maintain, a reluctance to submit himself to cross-examination? On his blog, as in the piazzas he has filled, the communication is essentially one way.