In ~25 years of cycling, I've been in two situations where a helmet most likely saved me from severe concussion and probably a fractured skull. Neither accident was solely my fault. A bicycle helmet is not "safety symbolism", it has verifiable benefits in reducing the severity of head injuries. Your phrasing and choice of words seem to suggest that people should just "harden up" and "things were better in the old days", which is a highly problematic position to take, one which smacks of rose-tinted glasses.
By your reasoning, motorcycle helmets and protective clothing is also pointless. After all, I've had no accidents in ~10 years of motorcycling, so the safety gear must be completely pointless? Nevertheless, I would never get on a motorcycle without proper gear, because I've seen the damage that can happen. I've also seen the head trauma that can happen in a bicycle crash, so I wear a helmet.
I'm not sure why you think people wearing helmets are casting votes for mandatory helmet laws. I'm certainly not a proponent of such laws, but I am very much a proponent of wearing a helmet, in order to reduce the severity of injuries. I am certain the vast majority of helmet wearers agree with me, we put on the helmet by choice, not because we want to force others to do the same.
The most dangerous cyclists are the ones constantly on their phones and/or with loud music in their ears. Same as car/truck drivers. The hardcore lycra-clad cyclists go rather fast, but they're also highly aware of their surroundings. Your experience from the limited visibility of a truck driver's seat is leading you to false conclusions.