I’m sorry. I don’t have enough information to tell you why your neighbor behaves this way. At his age, he could be suffering from dementia (although this started when he was younger so that is unlikely). He could also be suffering from a mental illness. Regardless of the reason: his behavior ranges from nuisance to criminal.
I don’t know why the police won’t respond. Perhaps they are only getting complaints one at a time over years and don’t see the pattern. Maybe if you and the neighbors all got together at the same time and invited the police to a meeting where you would all list the many things that have occurred, the police would understand that the neighbor is truly a danger to others, not just a cranky old man. I don’t know enough about the system of justice in Croatia to make any further suggestions. Do talk to a legal expert if you can.
In the meantime, please do everything you can to stay safe. This gentleman has already shown that he is capable of hurting people.
I wish you well.