Robbers carry out their vicious attacks for 'kicks' and street credibility rather than cash, a chilling study reveals.
The research, based on interviews with 120 sentenced criminals, said others simply had a desire for brutal violence.
Past research has blamed a surge in violent robberies on offenders trying to get their hands on money, often to pay for drugs.
But Economic and Social Research Council said links to gangs and the need to gain 'street cred' were also a huge motivating factor.
Up to a third of those questioned - a group which included thugs arrested on more than 50 occasions - said they were involved in gangs or criminal groups.
The study, by Professor Trevor Bennett and Dr Fiona Brookman, added: 'Both the amount and the severity of gratuitous violence used in street robbery are increasing in the UK.
'But because the number of studies is very small, and tends to be limited to what the precise situation was in each case and whether the assault was likely to lead to financial gain, this worrying social problem is poorly documented and understood.'
Interviews with offenders reveal that some found robbery to be a pleasurable activity in its own right.
One offender said he was addicted to it, the study said. 'It weren't even for money. I had money. It was more like the buzz you get from doing things,' one convict said.
'I was more addicted to robbing than I was to drugs. Just get a funny feeling when I go out robbing.'
The authors said one element in the excitement felt by the violent offenders came from overpowering the victim and obtaining dominance.
'It's for the fun. 'Cos the point of street robbery is to get them to fight back, innit? I'd give him a couple of slaps and tell him to fight back,' said one criminal. If he won't fight back, we just give him a kick and go.'
Sometimes, theft was only an afterthought, with the crime being prompted by 'anger and the desire to start a fight', the report says.
'I picked a fight with someone on the street. They were the first people I come across,' said one thug. 'I started hitting one of them and calling him names and said, 'What are you looking at?' and stuff like that.
'Then I can't remember how, but I started hitting him and then I just jumped on him. Punched him, turned him over, went through his pockets.'
The average age of those interviewed, in six jails across the country, was 26. Over a quarter (28 per cent) carried firearms and an additional 35 per cent carried some other weapon, usually a knife. In all, 92 per cent had used illegal drugs. Cash made from crime was often spent on 'non-essential, status-enhancing' items. Professor Bennett said: 'The decision to commit street robbery can be explained in part by particular characteristics of the street culture. 'This finding is important, because British research has tended to explain robbery in terms of rational choice and to focus instead on the role of cost-reward calculations. Of those quizzed, 36 per cent had been arrested more than 50 times, 17 per cent between 25 and 49 times and 30 per cent between 10 and 24 times.