Chaiya Somsrichan, a 26-year-old straw-press operator, was found dead in his house in Song Phi Nong district with an empty pesticide bottle by his side, according to a Thai Rath Online report.
There was no sign of a struggle or injuries.
Pol Maj Somporn Porntaniskul of the district police station found Chaiya in his bedroom with the television turned on.
Iang Roongcharoen, his mother, said Chaiya had been very keen on the World Cup 2014 games.
He brought friends home to watch every match.
She figured he might have lost heavily when gambling on the football because some loan sharks came looking for him every day, the report said.
Before his death, Chaiya asked to borrow 10,000 baht from his mother but she gave him only 200 baht and scolded him.
His friends also told her Chaiya had placed a bet on the Brazil team, hoping to get the money to repay his debts.
Brazil's 7-1 loss to Germany early today might have driven him to desperation, Mrs Iang said.