Pete. I often ride alone. don't mind it. Do suspect you are safer in a bike pack. Wacko motor primates- Chris' term- probably they are less brazen; if there are witness'.
But I always commute alone. Maybe ride 3-5 times a week on average. I'd say 2 times is alone. Alone is often good. can go where you want, stop where you want. Be alone and let your thoughts wonder, mabye resolve some issues. Does not take a group to motivate me to get out, but when with a group- good to share in that cycling community spirit. That is fun times too.