Police have released CCTV footage of the moment customers, including a 75-year-old man, wrestled a knife-wielding robber to the floor.
Darren Burke, 39, was jailed for four years on Friday after admitting the robbery at a Ladbrokes betting shop in Bath on 24 June.
Bristol Crown Court heard how he leaped over the counter to grab £3,200.
But Burke's escape was blocked by a member of staff and three customers, including Peter Greensides, 75.
Burke, of no fixed abode, was arrested at the scene.
Mr Greensides, from Bath, said: "I do not think I am a hero. Adrenalin just kicked in.
"Afterwards I felt a bit shaken up, and had bruised my knees and back."