'I'm doing this because I think I need to create a spark in the middle and let the fire take its own (shape),' he told AFP in a rare interview.
Speaking in a canteen on the occupied grounds of Government House, Mr Sondhi portrays himself as a patriot leading thousands of supporters of his People's Alliance for Democracy (PAD) to save the country from cronyism.
'It takes many pressures to make society move, and the PAD is probably one of the biggest pressure groups which is doing the job,' he said in impeccable English.
Prime Minister Somchai Wongsawat is certainly feeling the pressure, saying he may resign in the face of the anti-government protests which began in May and spilled over into street clashes with police last week that left two dead and several hundred injured.
Mr Sondhi and other core PAD leaders were briefly jailed and then released on bail last week, after insurrection charges were dropped against them.
They are a disparate collection of right- and left-wing leaders united by their championing of the revered Thai monarchy - and their determination to bring down the ruling party.
Mr Sondhi alleges the People Power Party was elected in Dec 2007 through vote-buying and corruption, and that 'political parties are being run like an investment bank.'
'This kind of politics no longer works in Thailand. We need a new system - we need new politics,' he said.
Asked to clarify, he answered, 'We have not gone into the nitty-gritty of what new politics should be, but at least we are saying to ourselves: let's forget about the old ways of running politics.'
Mr Sondhi has been branded elitist and anti-democratic by critics because he has in the past said 70 per cent of the seats in parliament should be filled by appointment, with only 30 per cent decided by popular vote.
Mr Sondhi now laughs and says he was misunderstood.
'It's a joke,' he said. 'When I was mentioning that, I was simply giving a model and I said it could be anything, for instance 70-30. And I was going to say it could be 50-50, it could be 10-90.'
However, he still maintains there are too many elected representatives in Thailand's parliament.
'Although I believe in direct elections, I don't believe direct elections in a society like Thailand should dominate democracy. It should be part of it.'
Mr Sondhi, 61, was better known as an ambitious media mogul until 2005. That was when he began his campaign to oust then-premier Thaksin Shinawatra - whom he had once declared the nation's 'best prime minister ever.'
The PAD was duly formed in early 2006.
Mr Sondhi because Thaksin's chief critics, denouncing him as corrupt, and led street protests which opened the way for the military to topple the government in a 2006 military coup.
Thaksin said Mr Sondhi wanted revenge after the media tycoon invested heavily in a new television station that was blocked by regulatory hurdles.
Mr Sondhi admits finances are lagging at his Manager Media Group, but in his newer role as political campaigner he says the PAD movement has received some 130 million baht (S$5.6 million) in donations from all over Thailand since late May.
But the protest leader, who alleges Thaksin still controls the government from self-imposed exile in Britain, insists his own business interests have nothing to do with his campaigning.
'The amount of energy, the amount of danger I've been through is not worth it if I don't have the principle to fight,' he said, adding he has no designs to enter politics himself.
'Trust me, there is actually someone who wants to do something good.' -- AFP