Today, his celebrated riches-to-rags story is centre stage in his second career as the owner of a food and drinks company. He declared bankruptcy in 2003, owing nearly 1 billion baht in debt, but is now solvent again.

Despite his recovery at the helm of Sirivat Sandwich, he is sanguine about the risks of expanding too fast. He worries that the lessons of the crisis have not been learned in Thailand and that consumers are piling up debt they can not afford to service. At the counter of one of the two coffee shops that he runs in Bangkok, Mr Sirivat, 58, poses next to a life-sized cardboard cut-out of him in a white cap, carrying his sandwich box with the company logo on the front.

'It's like KFC's Colonel Sanders, except that I'm younger than him,' he joked.

Back in the go-getting 1990s, Mr Sandwich had another nickname: the Phantom. He earned it by pouncing on stocks after a global sell-off, just at the moment when the market recovered. Investors made a beeline to Asia Securities, his brokerage to entrust him with their money and he began to dream up more get-rich schemes.

One of those was property. Mr Sirivat borrowed heavily to develop a resort condominium by Khao Yai national park outside Bangkok, betting that high rollers would snap up luxury homes for golfing weekends.

He was a multimillionaire, at least on paper. His three children attended summer school in Britain and New Zealand and his family lived in the most exclusive condominium in Bangkok, along with other celebrated tycoons.

But his property investment was ill-timed. The baht's devaluation in 1997 from a fixed peg of 25 to the US dollar forced his debt-carrying tycoon customers to tighten their belts and Mr Sirivat was left high and dry with the cement still drying on the unwanted condo units. Most had only collected a 10 per cent deposit. The other 90 per cent never arrived.

His creditors kept calling and he stopped going to the office where his staff were left wondering if their salaries would be paid. Deeply in debt and pursued by lenders, Mr Sirivat saw his fortune quickly evaporate as Bangkok's stock market plunged and foreign banks cut off credit lines.

Unlike some private businessmen, though, he does not pin the blame for his credit crunch on bankers or speculators. He sees himself as a victim of market forces, but not a wholly innocent one.

'I was very greedy,' he sighed. 'I never had enough. I thought whatever I do I must be successful, it was my ego.'

Stressed and unable to sleep, Mr Sirivat realised that bankruptcy was staring him in the face. But there had to be a way to make a living and provide for his family and employees. Even in a recession, he thought, people still had to eat.

So one morning he loaded 80 sandwiches into a polystyrene box and attached a strap around his neck. The lid of the box could be flipped to display the sandwiches that he and his wife had made that morning.

The idea came from the roaming popcorn and bubblegum sellers that he had seen at sports events when he was a student at the University of Texas in Austin in the 1970s. Most street vendors in Bangkok carry baskets or set up tables to sell their wares.

That first day, Mr Sirivat stood on a busy corner with his box, watching commuters pass by in their smart suits. For the first half hour, nobody bought a sandwich and his heart sank. Then, as lunchtime drew closer, he began to unload his stock. The next day, he was back on the same spot.

A Thai newspaper ran a story on the 'formerly rich' stockbroker who was selling sandwiches on the streets. Other media picked up on the story and Mr Sandwich began appearing on the cover of foreign magazines.

One day, a female flower vendor came up to him and asked if he was the bankrupt businessman that she had read about in a local newspaper. He nodded. She then bought two sandwiches costing 30 baht each, three times the price of a bowl of noodles, and said she wanted to support him.

That a poor vendor would shell out on a sandwich priced for office yuppies was a gesture that resonated with Mr Sirivat. 'She said, 'don't be afraid, at least you have fighting spirit. And today I can say that all those flower vendors at that intersection are all my friends,' he said.

The same can't be said of the wealthy golfing buddies he acquired during his meteoric rise to the top. 'When I was rich I had many friends. But when I went bankrupt my friends only gave words of encouragement. They were still rich but they didn't buy my sandwiches,' he said.

Eventually the creditors closed in, seizing the luxury condo, two plots of land in Bangkok and Khao Yai and his mother's home that he had put up as collateral. The globe-trotting family holidays were over.

In 2006, Mr Sirivat finally emerged from bankruptcy, determined to make a success of his new venture.

From its humble beginnings, Sirivat Sandwich has grown along with the Thai economy. It employs teams of mobile vendors at subway stations and downtown junctions, provides catering to offices and is expanding its Coffee Corner outlets around the city. Its range of take-out meals now includes brown-rice sushi and other healthy options.

But the former stock guru is bearish on Thailand's economic prospects, spying a correction around the corner despite the pick-up in stock prices in recent months. He points to rising personal debt levels, falling foreign investment and the steady climb in pump prices as reasons to be cautious, if not downright pessimistic. Today's spenders are tomorrow's debtors.

'Ten years on, I'm not sure Thai people have learned anything. Thai people seem to forget things very fast,' he fretted.

Nevertheless, the former Phantom is hoping to dip his toes in the capital markets again. Within two years, if the Coffee Corner expansion goes well, he wants to list the company on Bangkok's alternative market for small businesses.

He also reckons that a foreign partner may want to get a piece of the action, provided it has food and beverage expertise.

He has not completely hung up his famous sandwich box. Occasionally he goes out on the streets with his team to hawk wares to passers-by, who stop and ask if he's the tycoon who fell to earth with a bump in 1997.

'Today people want to know how you recovered, how you do it. I say I did it because of support from people. Thai people come to help me,' he said.