It's quite possible that someone that inconsiderate would have treated you the same way regardless if you had an engine beneath you or not. When I commuted on a motorcycle I twice had people encroach into half of the lane I was riding in while passing me at high speed - and coming quite close to hitting me in the process. Perhaps they felt justified because they sometimes get passed by motorcycles splitting lanes - that is, sharing the same lane with a car when traffic slows or stops altogether. Perhaps they simply didn't care if they frightened and/or endangered me by their reckless driving. It is also possible they - as well as the young man who offended you - had been likewise offended by a motorcyclist or bicyclist in the past. That's the reason I do my best not to offend anyone in a car. This includes running traffic lights and stop signs or otherwise taking someone elses right of way. Even if they don't catch up to me, they might take it out on the next cyclist they encounter.