This is btw also why cyclist's rights organizations (e.g. fietsersbond in NL) should be _against_ mandatory use of helmets. Helmets make it less convenient to cycle and reduces perceived safety, in turn reducing the amount of cyclists and as a result _actually_ making cycling less safe (and the vicious circle ensues).
Even only suggesting that it would be beneficial to use a helmet has this effect apparently, hence the organizations are only willing to state that they are "not against the use of helmets".
Just an interesting second order effect I think. You want to always be careful to optimize for the absolute number of safe rides, and not solely for the relative number of safe rides that might significantly reduce the absolute number of safe rides.
Not mandatory and at your own risk IMO, but as a simple thought exercise on your argument, answer me this: if a car hits you on your bike or another cyclists knocks you off your bike and your head hits the concrete/kerb, are you gonna escape better off from the accident with or without wearing a helmet?
Spoiler alert from my GFs sister who works at an ER in Austria: helmeted patients walk away without permanent brain injury which she can't say the same for those involved in accidents without helmets. Helmets saving lives isn't a lobby issue, it's a medical fact.
People telling you to not wear a helmet because it somehow reduces safety through some convoluted spaghetti argument, must be off their rockers, when they clearly save lives at impacts. That's like saying governments should be against mandatory seatbelts and airbags in cars because their added safety encourages a cycle of unsafe driving leading to more accidents, and that without them divers would be forced to drive more carefully and lead to more safety.
It's perfectly fine to militate for the utopia of building of safe cycling infrastructure everywhere for everyone, but please let's not unnecessarily put people's lives at risk by promoting this FUD that helmets don't increase safety, just so people can literally die on this hill.
By all means, each individual should do of course as they see fit according to their desired risk profile of where they live and how they want to live their lives, just don't ask others to put their lives in danger in order to emulate the lifestyle where you live where the risks for not wearing a helmet are much smaller.