Actually if you have ever ridden a bike for any length of time, you will realise that many drivers of vehicles with 4 wheels or more, are , and can be rather aggressive, and especially after hours on weekends, returning home from clubbing or a party.
The drivers know they have the protection of metal all around them as opposed to the bike, so having a means to deter aggression, or to counter acts of aggression, is self preservation.
Why do bikers travel in packs normally?, safety on the road. A couple of youngsters joy riding wouldnt hesitate to mess around with 1 lone biker, if they thought they could get away with it, however they would think twice if there are 10 bikers, so the insurance is for those occasions when one is alone.
Live the experience alone on a bike, and then come talk again, and see how you feel, (if you survive the incident that is)