Thomas McNally got his fingers burned as his near £1,000 haul went up in smoke, Wolverhampton Crown Court heard. The 23-year-old accidentally set light to the money while torching clothes he had worn as he struck at Ladbrokes in Bushbury Road, Bushbury, armed with a knife at 8.15pm on December 18.
He had waited until there were no customers and only one female member of staff on the premises, explained Mr Paul Spratt, prosecuting.
The lawyer continued: "He approached the cash desk, handed over a bag and ordered the woman to put money into it. The knife was clearly visible. She managed to press an alarm hanging round her neck and left it on so that security staff could hear what was happening. The defendant was persistent and wanted money from the safe as well."
McNally escaped with £910 but phoned police the following day to admit what he had done, the court heard.
Mr Spratt revealed: "Officers went to his address and he asserted that it had not been a real knife. He also said that he had burned both his clothes and the money, the latter in error. He explained that he had been drinking all day and was in significant debt."
Miss Aimee Parkes, defending, declared: "The threat of the robbery only lasted a couple of minutes and nobody was injured. He did have a knife but claims the blade was plastic.
"He owed £4,000 after his gambling got out of control and was also under pressure to buy Christmas presents for his two children who do not live with him. He knows he has been stupid and has let his children down but was under pressure from his family and his gambling debts."
Rail employee McNally from Leacroft Avenue, Low Hill admitted robbery and was jailed for two years eight months by Judge John Wait who told him: "This was a serious offence. You were expecting to get substantial rewards from the bookmakers which you could see was not heavily staffed.
"But you have done a great deal to give yourself maximum credit by handing yourself in the next day. That is the best expression of remorse you could have displayed."