In contrast with a few respondents who don't have cameras and feel it would make them aggressive or dangerous, I find I ride a lot more calmly when I'm recording and am much more likely to side-step a confrontation.
Having said that, I think it's only a secondary benefit to being able to watch back my own riding and understand what's going on. I learned a huge amount from watching people's youTube channels and being able to play back your own incidents is even more valuable. Especially at first, where you watch back something where you felt 100% in the right and end up thinking "wait a minute, I'm riding like a tit there".
Thirdly, interesting stuff happens from time to time. I've videoed three good 'offs' of my own as well as an entertaining crash by another rider.
Having video evidence against the minute chance that I'm going to get levelled by someone is a (very) distant justification. Ironically, I was once taken out by a hit-and-run driver (pre-camera days) and if I'd been wearing mine they'd have been in hot water, instead of getting off scot free (they saw me before the crash because they were shouting at me to get out of their way while they accellerated through the space I was occupying).