But, the crisis turned him from a wealthy man into the "sandwich man". From easy street to the streets, Sirivat began a new life, selling freshly-made sandwiches at crowded intersections in Bangkok's business areas like Sukhumvit, Silom and Phloenchit roads.
The yellow box strung from his neck as he sold workers their lunch has endured to become a symbol. It tells the story of the hard times he and his wife overcame in the past 10 years.
He will never forget his first day - six hours to sell 20 sandwiches. "I had my family - my wife and three children - as well as 40 staff to take care of," Sirivat said of that day.
No friends, no relatives and no bank to help him with money. He was a broken man.
Yet Sirivat grew his new business with the little money left with him after his debts had been cleared.
Five years ago, he decided to open the first of his new coffee-shops - Coffee Corner by Sirivat Sandwich, in BNH Hospital. Last year, another opened at Bangkok Hospital on Rama IX Road.
He makes all of his quick and ready-to-eat foods from local rice and fruit. Even though his earnings are a fraction of those of 10 years ago, he is happy doing "the real thing; no bubbles".
"I like my business to proceed step by step," he said.
The lessons of the crisis taught him the meaning of sufficiency, sustainability and patience.
Sirivat patiently makes an effort to ensure that his business will be sustainable. He plans to go public over the next two years.
His business model guarantees that wherever he opens a new coffee-shop, he recruits locals as staff and sources products from inside the province.
He will use local graduates and teach them about running a business - and how not to run a business. He said it would be like a post-graduate course on the job.
Sirivat's goal is simple and ambitious: "If McDonald's aims to sell to just 1 per cent of the world's 6 billion people, then I want to sell to just 1 per cent of Thailand's 65 million," he said.